CVE-2026-42008

dovecot: Dovecot: Authentication bypass via trusted proxy forwarding

Published Aug 28, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
Forwarding information received from a host listed as a trusted proxy is not kept separate from Dovecot's own authentication fields, so a value sent by that host can be injected as an internal authentication field. Any host permitted to act as a trusted proxy can authenticate as any user without knowing that user's password. This affects deployments whose password database honours a field that permits authentication without a password. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-4873-1 dovecot security update
Debian DSA Debian DSA DSA-6526-1 dovecot security update
History
Type Values Removed Values Added
First Time appeared Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro
Vendors & Products Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro
Type Values Removed Values Added
Title Trusted Proxy Authentication Bypass in OX Dovecot dovecot: Dovecot: Authentication bypass via trusted proxy forwarding
Weaknesses CWE-349
References
Metrics threat_severity

None

threat_severity

Moderate

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Trusted Proxy Authentication Bypass in OX Dovecot
Type Values Removed Values Added
Description Forwarding information received from a host listed as a trusted proxy is not kept separate from Dovecot's own authentication fields, so a value sent by that host can be injected as an internal authentication field. Any host permitted to act as a trusted proxy can authenticate as any user without knowing that user's password. This affects deployments whose password database honours a field that permits authentication without a password. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.
Weaknesses CWE-287
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
OX
Published
Updated
Aug 28, 2026, 3:54 PM
Reserved
Apr 23, 2026, 11:15 AM
Status
Deferred
Published
Aug 28, 2026, 12:16 PM
Modified
Sep 3, 2026, 6:13 PM
Severity
Moderate
Public date
Aug 28, 2026, 10:12 AM