Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.

debian_linux dla-4556: Debian dla-4556 : dovecot-auth-lua - security update

The remote MiracleLinux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the AXSA:2026-567:01 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)
      * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)
      * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the MiracleLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote RockyLinux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:13857 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the RockyLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-51dba40a65 advisory.

    updated to 2.4.3 which includes several security fixes

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-4349d04c20 advisory.

    updated to 2.4.3 which includes several security fixes

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote RockyLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:13830 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the RockyLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote AlmaLinux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALSA-2026:13498 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)
      * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)
      * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the AlmaLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2026-13830 advisory.

    - fix CVE-2026-27858: denial of service via crafted message before authentication (RHEL-161630)
    - fix CVE-2025-59032: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE     command (RHEL-162282)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2026-13857 advisory.

    - fix CVE-2026-27858: denial of service via crafted message before authentication (RHEL-161639)
    - fix CVE-2025-59032: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE     command (RHEL-162287)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote RockyLinux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:13498 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the RockyLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2026-13498 advisory.

    - fix CVE-2026-27858: denial of service via crafted message before authentication (RHEL-161625)
    - fix CVE-2025-59032: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE     command (RHEL-162273)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote AlmaLinux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALSA-2026:13830 advisory.

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)
      * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)
      * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the AlmaLinux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:13857 advisory.

    Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind.
    It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL     drivers and authentication plug-ins are provided as subpackages.

    Security Fix(es):

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:13830 advisory.

    Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind.
    It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL     drivers and authentication plug-ins are provided as subpackages.

    Security Fix(es):

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:13498 advisory.

    Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind.
    It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL     drivers and authentication plug-ins are provided as subpackages.

    Security Fix(es):

    * dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command     (CVE-2025-59032)

    * dovecot: denial of service via crafted message before authentication (CVE-2026-27858)

    * dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES12 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:1641-1 advisory.

    - CVE-2025-59031: decode2text.sh OOXML extraction may follow symlinks and read unintended files during     indexing (bsc#1260895).
    - CVE-2025-59032: pigeonhole: ManageSieve panic occurs with sieve-connect as a client (bsc#1260902).
    - CVE-2026-27855: OTP driver vulnerable to replay attack (bsc#1260900).
    - CVE-2026-27856: Doveadm credentials were not checked using timing-safe checking function (bsc#1260899).
    - CVE-2026-27857: sending excessive parenthesis causes imap-login to use excessive memory (bsc#1260898).
    - CVE-2026-27858: pigeonhole: managesieve-login can allocate large amount of memory during authentication     (bsc#1260901).
    - CVE-2026-27859: excessive RFC 2231 MIME parameters in email would can excessive CPU usage (bsc#1260897).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of dovecot installed on the remote host is prior to 2.2.36-6. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3252 advisory.

    Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An     attacker can use this to determine the configured credentials. Figuring out the credential will lead into     full access to the affected component. Limit access to the doveadm http service port, install fixed     version. No publicly available exploits are known. (CVE-2026-27856)

    Sending NOOP (((...))) command with 4000 parenthesis open+close results in ~1MB extra memory usage.
    Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time     periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and     create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and     killing the process and its other proxied connections. Attacker could connect possibly from even a single     IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit     and killing the process and its other proxied connections. Install fixed version, there is no other     remediation. No publicly available exploits are known. (CVE-2026-27857)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:20554-1 advisory.

    - Update to v2.4.3
    - CVE-2025-59028: Invalid base64 authentication can cause DoS for other logins (bsc#1260894).
    - CVE-2025-59031: decode2text.sh OOXML extraction may follow symlinks and read unintended files during     indexing       (bsc#1260895).
    - CVE-2025-59032: pigeonhole: ManageSieve panic occurs with sieve-connect as a client (bsc#1260902).
    - CVE-2026-24031: SQL injection possible if auth_username_chars is configured empty. Fixed escaping to     always happen.
      v2.4 regression (bsc#1260896).
    - CVE-2026-27855: OTP driver vulnerable to replay attack (bsc#1260900).
    - CVE-2026-27856: Doveadm credentials were not checked using timing-safe checking function (bsc#1260899).
    - CVE-2026-27857: sending excessive parenthesis causes imap-login to use excessive memory (bsc#1260898).
    - CVE-2026-27858: pigeonhole: managesieve-login can allocate large amount of memory during authentication     (bsc#1260901).
    - CVE-2026-27859: excessive RFC 2231 MIME parameters in email would can excessive CPU usage (bsc#1260897).
    - CVE-2026-27860: LDAP query injection possible if auth_username_chars is configured empty. Fixed escaping     to always       happen. v2.4 regression (bsc#1260893).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES16 / SLES_SAP16 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:21208-1 advisory.

    - Update to v2.4.3
    - CVE-2025-59028: Invalid base64 authentication can cause DoS for other logins (bsc#1260894).
    - CVE-2025-59031: decode2text.sh OOXML extraction may follow symlinks and read unintended files during     indexing       (bsc#1260895).
    - CVE-2025-59032: pigeonhole: ManageSieve panic occurs with sieve-connect as a client (bsc#1260902).
    - CVE-2026-24031: SQL injection possible if auth_username_chars is configured empty. Fixed escaping to     always happen.
      v2.4 regression (bsc#1260896).
    - CVE-2026-27855: OTP driver vulnerable to replay attack (bsc#1260900).
    - CVE-2026-27856: Doveadm credentials were not checked using timing-safe checking function (bsc#1260899).
    - CVE-2026-27857: sending excessive parenthesis causes imap-login to use excessive memory (bsc#1260898).
    - CVE-2026-27858: pigeonhole: managesieve-login can allocate large amount of memory during authentication     (bsc#1260901).
    - CVE-2026-27859: excessive RFC 2231 MIME parameters in email would can excessive CPU usage (bsc#1260897).
    - CVE-2026-27860: LDAP query injection possible if auth_username_chars is configured empty. Fixed escaping     to always       happen. v2.4 regression (bsc#1260893).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1570 advisory.

    Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An     attacker can use this to determine the configured credentials. Figuring out the credential will lead into     full access to the affected component. Limit access to the doveadm http service port, install fixed     version. No publicly available exploits are known. (CVE-2026-27856)

    Sending NOOP (((...))) command with 4000 parenthesis open+close results in ~1MB extra memory usage.
    Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time     periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and     create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and     killing the process and its other proxied connections. Attacker could connect possibly from even a single     IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit     and killing the process and its other proxied connections. Install fixed version, there is no other     remediation. No publicly available exploits are known. (CVE-2026-27857)

    Attacker can send a specifically crafted message before authentication that causes managesieve to allocate     large amount of memory.Attacker can force managesieve-login to be unavailable by repeatedly crashing the     process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits     are known. (CVE-2026-27858)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6197 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6197-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     April 05, 2026                        https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : dovecot     CVE ID         : CVE-2025-59031 CVE-2025-59032 CVE-2026-27855                      CVE-2026-27856 CVE-2026-27857 CVE-2026-27858                      CVE-2026-27859 CVE-2026-59028 CVE-2026-24031                      CVE-2026-27860 CVE-2026-0394

    Multiple vulnerabilities have been discovered in the Dovecot IMAP server     which way result in denial of service, SQL injection, path traversal,     replay attacks or timing side channel attacks.

    For the oldstable distribution (bookworm), these problems have been fixed     in version 1:2.3.19.1+dfsg1-2.1+deb12u2.

    For the stable distribution (trixie), these problems have been fixed in     version 1:2.4.1+dfsg1-6+deb13u4.

    We recommend that you upgrade your dovecot packages.

    For the detailed security status of dovecot please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/dovecot

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8136-1 advisory.

    It was discovered that Dovecot incorrectly handled invalid base64 SASL data. An attacker could possibly     use this issue to cause a denial of service. This issue only affected Ubuntu 25.10. (CVE-2025-59028)

    It was discovered that Dovecot script decode2text.sh incorrectly handled zip files. An attacker could     possibly use this issue to obtain sensitive information. (CVE-2025-59031)

    It was discovered that Dovecot incorrectly handled certain AUTHENTICATE requests. An attacker could     possibly use this issue to cause a denial of service. (CVE-2025-59032)

    It was discovered that Dovecot incorrectly handled certain SQL based authentication. An attacker could     possibly use this issue to bypass authentication. This issue only affected Ubuntu 25.10. (CVE-2026-24031)

    It was discovered that Dovecot incorrectly handled certain LDAP based authentication. An attacker could     possibly use this issue to bypass restrictions and allow probing of LDAP structure. This issue only     affected Ubuntu 25.10. (CVE-2026-27860)

    It was discovered that Dovecot is vulnerable to replay attack under certain conditions. An attacker could     possibly use this issue to bypass authentication. (CVE-2026-27855)

    It was discovered that Dovecot is vulnerable to a timing attack under certain conditions. An attacker     could possibly use this issue to bypass authentication. (CVE-2026-27856)

    It was discovered that Dovecot incorrectly handled certain IMAP login requests. An attacker could possibly     use this issue to cause a denial of service. (CVE-2026-27857)

    It was discovered that Dovecot incorrectly handled certain specially crafted messages. An attacker could     possibly use this issue to cause a denial of service. (CVE-2026-27858)

    It was discovered that Dovecot incorrectly handled certain specially crafted mail messages. An attacker     could possibly use this issue to cause a denial of service. (CVE-2026-27859)

    It was discovered that Dovecot incorrectly handles file paths. A attacker could possibly use this issue to     perform a path traversal and obtain or modify arbitrary files. This issue only affected Ubuntu 22.04 LTS     and Ubuntu 24.04 LTS. (CVE-2026-0394)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Sending NOOP (((...))) command with 4000 parenthesis open+close results in ~1MB extra memory usage.
    Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time     periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and     create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and     killing the process and its other proxied connections. Attacker could connect possibly from even a single     IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit     and killing the process and its other proxied connections. Install fixed version, there is no other     remediation. No publicly available exploits are known. (CVE-2026-27857)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
313230	MiracleLinux 9 : dovecot-2.3.16-15.el9_7.1 (AXSA:2026-567:01)	Nessus	Miracle Linux Local Security Checks	high
313035	RockyLinux 9 : dovecot (RLSA-2026:13857)	Nessus	Rocky Linux Local Security Checks	high
313033	Fedora 43 : dovecot (2026-51dba40a65)	Nessus	Fedora Local Security Checks	high
313028	Fedora 44 : dovecot (2026-4349d04c20)	Nessus	Fedora Local Security Checks	high
313014	RockyLinux 8 : dovecot (RLSA-2026:13830)	Nessus	Rocky Linux Local Security Checks	high
312682	AlmaLinux 10 : dovecot (ALSA-2026:13498)	Nessus	Alma Linux Local Security Checks	high
312677	Oracle Linux 8 : dovecot (ELSA-2026-13830)	Nessus	Oracle Linux Local Security Checks	high
312673	Oracle Linux 9 : dovecot (ELSA-2026-13857)	Nessus	Oracle Linux Local Security Checks	high
312381	RockyLinux 10 : dovecot (RLSA-2026:13498)	Nessus	Rocky Linux Local Security Checks	high
312317	Oracle Linux 10 : dovecot (ELSA-2026-13498)	Nessus	Oracle Linux Local Security Checks	high
312294	AlmaLinux 8 : dovecot (ALSA-2026:13830)	Nessus	Alma Linux Local Security Checks	high
312286	RHEL 9 : dovecot (RHSA-2026:13857)	Nessus	Red Hat Local Security Checks	high
312251	RHEL 8 : dovecot (RHSA-2026:13830)	Nessus	Red Hat Local Security Checks	high
312101	RHEL 10 : dovecot (RHSA-2026:13498)	Nessus	Red Hat Local Security Checks	high
311743	SUSE SLES12 Security Update : dovecot22 (SUSE-SU-2026:1641-1)	Nessus	SuSE Local Security Checks	medium
311199	Amazon Linux 2 : dovecot, --advisory ALAS2-2026-3252 (ALAS-2026-3252)	Nessus	Amazon Linux Local Security Checks	medium
309138	openSUSE 16 Security Update : dovecot24 (openSUSE-SU-2026:20554-1)	Nessus	SuSE Local Security Checks	high
309128	SUSE SLES16 Security Update : dovecot24 (SUSE-SU-2026:21208-1)	Nessus	SuSE Local Security Checks	high
306220	Amazon Linux 2023 : dovecot, dovecot-devel, dovecot-mysql (ALAS2023-2026-1570)	Nessus	Amazon Linux Local Security Checks	medium
305037	Debian dsa-6197 : dovecot-auth-lua - security update	Nessus	Debian Local Security Checks	high
304437	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : Dovecot vulnerabilities (USN-8136-1)	Nessus	Ubuntu Local Security Checks	high
304082	Linux Distros Unpatched Vulnerability : CVE-2026-27857	Nessus	Misc.	high

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