Detections
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Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Dovecot vulnerabilities (USN-8365-1)

critical Nessus Plugin ID 318619

Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8365-1 advisory.

 It was discovered that Dovecot incorrectly treated some variable expansion pipelines as safe in authentication filters. An attacker could possibly use this issue to perform SQL or LDAP injection attacks. This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS. (CVE-2026-27851)

 It was discovered that Dovecot incorrectly verified SCRAM TLS channel binding in certain base64 exchanges.
 A remote attacker could possibly use this issue to obtain sensitive information in a machine-in-the-middle attack. (CVE-2026-33603)

 It was discovered that Dovecot incorrectly enforced Sieve script CPU limits. An attacker could possibly use this issue to cause Dovecot to use excessive resources, leading to a denial of service.
 (CVE-2026-40016)

 It was discovered that Dovecot incorrectly handled certain IMAP SETACL commands. An attacker could possibly use this issue to spam folders to other users. (CVE-2026-40020)

 It was discovered that Dovecot incorrectly handled excessive IMAP bracing. An attacker could possibly use this issue to cause Dovecot to use excessive resources, leading to a denial of service. (CVE-2026-42006)

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.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-8365-1

Plugin Details

Severity: Critical

ID: 318619

File Name: ubuntu_USN-8365-1.nasl

Version: 1.2

Type: Local

Agent: unix

Published: 6/4/2026

Updated: 6/4/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

CVSS Score Source: CVE-2026-27851

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:dovecot-imapd, p-cpe:/a:canonical:ubuntu_linux:dovecot-auth-lua, p-cpe:/a:canonical:ubuntu_linux:dovecot-mysql, p-cpe:/a:canonical:ubuntu_linux:dovecot-dev, p-cpe:/a:canonical:ubuntu_linux:dovecot-lmtpd, p-cpe:/a:canonical:ubuntu_linux:dovecot-flatcurve, cpe:/o:canonical:ubuntu_linux:25.10, p-cpe:/a:canonical:ubuntu_linux:dovecot-sieve, p-cpe:/a:canonical:ubuntu_linux:dovecot-ldap, p-cpe:/a:canonical:ubuntu_linux:dovecot-pgsql, p-cpe:/a:canonical:ubuntu_linux:dovecot-managesieved, p-cpe:/a:canonical:ubuntu_linux:dovecot-core, p-cpe:/a:canonical:ubuntu_linux:dovecot-lucene, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:dovecot-pop3d, p-cpe:/a:canonical:ubuntu_linux:dovecot-sqlite, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:dovecot-submissiond, p-cpe:/a:canonical:ubuntu_linux:dovecot-solr, p-cpe:/a:canonical:ubuntu_linux:dovecot-gssapi

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 6/2/2026

Vulnerability Publication Date: 5/12/2026

Reference Information

CVE: CVE-2026-27851, CVE-2026-33603, CVE-2026-40016, CVE-2026-40020, CVE-2026-42006

USN: 8365-1