RHEL 8 : dovecot (RHSA-2026:76763)

critical Nessus Plugin ID 363392

Synopsis

The remote Red Hat host is missing one or more security updates.

Description

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:76763 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: Dovecot: Denial of Service via IMAP ID command with excessive parameters (CVE-2026-42391)

* dovecot: Dovecot: Authentication bypass via incorrect OAuth2 token validation (CVE-2026-73208)

* dovecot: Dovecot: Denial of service via crafted email headers (CVE-2026-27852)

* dovecot: Dovecot: Denial of Service via truncated quoted argument in ManageSieve (CVE-2026-40019)

* dovecot: Dovecot: Denial of Service and potential message duplication via connection limit exhaustion (CVE-2026-33263)

* dovecot: Dovecot: Denial of Service in ManageSieve login process (CVE-2026-33605)

* dovecot: Dovecot: Arbitrary Code Execution via Sieve editheader use-after-free (CVE-2026-42007)

* dovecot: Dovecot: MySQL multi-byte escaping wrong (CVE-2026-40018)

Bug Fix(es) and Enhancement(s):

* Dovecot crashes when accessing mailbox with: Panic: file mail-user.c: line 229 (mail_user_deinit):
assertion failed: ((*user)->refcount == 1) (JIRA:RHEL-176273)

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.

Solution

Update the affected packages.

Plugin Details

Severity: Critical

ID: 363392

File Name: redhat-RHSA-2026-76763.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 10/6/2026

Updated: 10/6/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

Percentile: 57.58

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 8

Temporal Score: 5.9

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

CVSS Score Source: CVE-2026-42007

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

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

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

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:8, cpe:/o:redhat:rhel_eus:8.10, p-cpe:/a:redhat:enterprise_linux:dovecot-devel, p-cpe:/a:redhat:enterprise_linux:dovecot-mysql, p-cpe:/a:redhat:enterprise_linux:dovecot-pgsql, p-cpe:/a:redhat:enterprise_linux:dovecot-pigeonhole, p-cpe:/a:redhat:enterprise_linux:dovecot

Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 10/6/2026

Vulnerability Publication Date: 8/28/2026

Reference Information

CVE: CVE-2026-27852, CVE-2026-33263, CVE-2026-33605, CVE-2026-40018, CVE-2026-40019, CVE-2026-42007, CVE-2026-42391, CVE-2026-73208

CWE: 1286, 303, 770, 825, 835, 89, 910

RHSA: 2026:76763

Detections

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