An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal, which causes an out-of-bounds write when the ManageSieve service compiles the script. This causes memory corruption and an observed crash of the ManageSieve process, resulting in denial of service for script management. This might be able to be used for remote code execution. Disable the ManageSieve service if users do not need remote Sieve script management. Update to non-vulnerable version. No publicly available exploits are known.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6526 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6526-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     September 28, 2026                    https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : dovecot     CVE ID         : CVE-2026-27852 CVE-2026-33263 CVE-2026-33604 CVE-2026-33605                      CVE-2026-33606 CVE-2026-33607 CVE-2026-40013 CVE-2026-40014                      CVE-2026-40015 CVE-2026-40017 CVE-2026-40018 CVE-2026-40203                      CVE-2026-40204 CVE-2026-40205 CVE-2026-42007 CVE-2026-42008                      CVE-2026-42391 CVE-2026-42392 CVE-2026-42393 CVE-2026-42394                      CVE-2026-42395 CVE-2026-52681 CVE-2026-52687 CVE-2026-73208                      CVE-2026-73209     Debian Bug     : 1144639

    Multiple vulnerabilities have been discovered in the Dovecot IMAP server     which could result in denial of service, SMTP smuggling, information     disclosure, code injection via malformed Sieve scripts or bypass of ACL     restrictions.

    For the stable distribution (trixie), these problems have been fixed in     version 1:2.4.1+dfsg1-6+deb13u7.

    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 Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-8b8efbd2b8 advisory.

    - updated to 2.4.5, many 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-2026-2e6b786570 advisory.

    - updated to 2.4.5, many 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 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-e8a6485109 advisory.

    - updated to 2.4.5, many 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 openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21720-1 advisory.

    Update to 2.4.5.

    - CVE-2026-33263: `submission-login`: panic when `mail_max_userip_connections` is reached (bsc#1276794).
    - CVE-2026-27852: DoS by sending mail with bad header (bsc#1276799).
    - CVE-2026-33604: SMTP smuggling via missing dot-stuffing after bare carriage return (bsc#1276802).
    - CVE-2026-33605: `managesieve-login`: pre-auth crash (bsc#1276809).
    - CVE-2026-33606: `dsync`: mail content can cause `dsync` protocol injection (bsc#1276800).
    - CVE-2026-33607: IMAP `LIST` `match_sub()` exponential backtracking leading to CPU denial of service     (bsc#1276795).
    - CVE-2026-40013: stack buffer underflow in `pigeonhole` `ManageSieve` `CHECKSCRIPT/PUTSCRIPT`     (bsc#1276807).
    - CVE-2026-40014: CPU DoS via crafted references header (bsc#1276804).
    - CVE-2026-40015: `imap-hibernate` can be crashed (bsc#1276812).
    - CVE-2026-40017: CPU DoS via CRC32 hash collision in `strmap` (bsc#1276813).
    - CVE-2026-40018: MySQL multi-byte escaping performed incorrectly (bsc#1276810).
    - CVE-2026-40203: IMAP compression can reveal whether a small synced email body matches sender-chosen text       (bsc#1276815).
    - CVE-2026-40204: `lda_mailbox_autocreate` can bypass ACL restrictions (bsc#1276819).
    - CVE-2026-40205: OAuth2 `passdb` scope enforcement bypass via OR semantics in remote validation path     (bsc#1276820).
    - CVE-2026-42007: `sieve` `editheader` RCE (bsc#1276817).
    - CVE-2026-42008: `XCLIENT FORWARD= bare` token not namespaced (bsc#1276824).
    - CVE-2026-42391: `imap`: pre-login memory/CPU growth with `ID` command (bsc#1276835).
    - CVE-2026-42392: `imap-urlauth` leaks memory into user-visible error messages (bsc#1276829).
    - CVE-2026-42393: `doveadm_password` or api key length can be leaked with timing comparisons     (bsc#1276827).
    - CVE-2026-52687: `imap`: `COMPRESS ZSTD` can cause excessive memory usage (bsc#1276837).
    - CVE-2026-42395: single NUL-byte `XCLIENT FORWARD` payload crashes (bsc#1276826).
    - CVE-2026-52681: `sieve` resource usage tracking lost when active script changes (bsc#1276828).
    - CVE-2026-73208: `auth`: `db-oauth2`: `aud` claim used as fallback for missing scope claim (bsc#1276830).
    - CVE-2026-73209: `imap-login` crash due to self-recursion on zero-output decompress chunks (bsc#1276833).

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

  - An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal,     which causes an out-of-bounds write when the ManageSieve service compiles the script. This causes memory     corruption and an observed crash of the ManageSieve process, resulting in denial of service for script     management. This might be able to be used for remote code execution. Disable the ManageSieve service if     users do not need remote Sieve script management. Update to non-vulnerable version. No publicly available     exploits are known. (CVE-2026-40013)

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

ID	Name	Product	Family	Type	Severity
350920	Debian dsa-6526 : dovecot-auth-lua - security update	Nessus	Debian Local Security Checks	Local	critical
348271	Fedora 45 : dovecot (2026-8b8efbd2b8)	Nessus	Fedora Local Security Checks	Local	critical
348254	Fedora 44 : dovecot (2026-2e6b786570)	Nessus	Fedora Local Security Checks	Local	critical
348253	Fedora 43 : dovecot (2026-e8a6485109)	Nessus	Fedora Local Security Checks	Local	critical
342588	openSUSE 16: dovecot24 / dovecot24-backend-mysql / dovecot24-backend-pgsql / etc (openSUSE-SU-2026:21720-1)	Nessus	SuSE Local Security Checks	Local	critical
341524	Linux Distros Unpatched Vulnerability : CVE-2026-40013	Nessus	Misc.	Local	medium

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