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

medium Nessus Plugin ID 321107

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4556 advisory.

------------------------------------------------------------------------- Debian LTS Advisory DLA-4556-1 [email protected] https://www.debian.org/lts/security/ Guilhem Moulin May 01, 2026 https://wiki.debian.org/LTS
-------------------------------------------------------------------------

Package : dovecot Version : 1:2.3.13+dfsg1-2+deb11u3 CVE ID : CVE-2025-59031 CVE-2025-59032 CVE-2026-0394 CVE-2026-27855 CVE-2026-27856 CVE-2026-27857 CVE-2026-27858 CVE-2026-27859

Multiple vulnerabilities were discovered in dovecot, a POP3/IMAP server, which could lead to Denial of Service, information leak, path traversal, authentication bypass, replay attacks or timing side channel attacks.

CVE-2025-59031

The decode2text.sh example script, which was installed into dovecot-core/examples, was found handle zip-style attachment in an unsafe manner. In particular, OOXML extraction may follow symlinks and read unintended files during indexing. The script is no longer installed.

CVE-2025-59032

It was found that the ManageSieve AUTHENTICATE command crashes the ManageSieve service when using literal as SASL initial response, leading to Denial of Service.

CVE-2026-0394

A pass traversal vulnerability was discovered in the passwd-file passdb/userdb when dovecot has been configured to use per-domain passwd files, allowing inadvertently reading /etc/passwd in some situations. If this file contains passwords, it can be used to authenticate wrongly, or if this is userdb, it can incorrectly make system users appear valid users.

CVE-2026-27855

The OTP authentication driver was found to be vulnerable to replay attack if auth cache is enabled the and username is altered in passdb. An attacker able to observe an OTP exchange is therefore able to impersonate the user.

CVE-2026-27856

Doveadm credentials were not checked using timing-safe checking functions. An attacker can exploit this issue to discover configured credentials, leading into full access to the affected component.

CVE-2026-27857

It was discovered that sending excessive parenthesis caused the imap-login process to use excessive memory, leading to Denial of Service.

CVE-2026-27858

It was discovered that the managesieve-login process could allocate large amount of memory during authentication via specifically crafted message, leading to Denial of Service.

CVE-2026-27859

It was discovered that excessive RFC 2231 MIME parameters in email would cause excessive CPU usage, which could lead to Denial of Service. Dovecot now limits the number of parameters to process.

For Debian 11 bullseye, these problems have been fixed in version 1:2.3.13+dfsg1-2+deb11u3.

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 LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS Attachment:
signature.asc Description: PGP signature

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.

Solution

Upgrade the dovecot-auth-lua packages.

Plugin Details

Severity: Medium

ID: 321107

File Name: debian_DLA-4556.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Debian Local Security Checks

Published: 6/15/2026

Updated: 6/15/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 5.4

Temporal Score: 4

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

CVSS Score Source: CVE-2026-27856

CVSS v3

Risk Factor: Medium

Base Score: 5.9

Temporal Score: 5.2

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

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

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:dovecot-lmtpd, p-cpe:/a:debian:debian_linux:dovecot-pgsql, p-cpe:/a:debian:debian_linux:dovecot-sqlite, p-cpe:/a:debian:debian_linux:dovecot-pop3d, p-cpe:/a:debian:debian_linux:dovecot-gssapi, p-cpe:/a:debian:debian_linux:dovecot-lucene, p-cpe:/a:debian:debian_linux:dovecot-managesieved, p-cpe:/a:debian:debian_linux:dovecot-submissiond, p-cpe:/a:debian:debian_linux:dovecot-sieve, p-cpe:/a:debian:debian_linux:dovecot-dev, p-cpe:/a:debian:debian_linux:dovecot-core, p-cpe:/a:debian:debian_linux:dovecot-auth-lua, p-cpe:/a:debian:debian_linux:dovecot-ldap, p-cpe:/a:debian:debian_linux:dovecot-mysql, p-cpe:/a:debian:debian_linux:dovecot-imapd, p-cpe:/a:debian:debian_linux:dovecot-solr

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/1/2026

Vulnerability Publication Date: 3/27/2026

Reference Information

CVE: CVE-2025-59031, CVE-2025-59032, CVE-2026-0394, CVE-2026-27855, CVE-2026-27856, CVE-2026-27857, CVE-2026-27858, CVE-2026-27859

Detections

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