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Full vulnerability report · 2026
CVE-2026-42008High confidence

Update to non-vulnerable version

Open-Xchange GmbH · OX Dovecot Pro

4.3MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Mitigation available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivedovecotUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 8 Sept 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-42008 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitydovecot: Dovecot: Authentication bypass via trusted proxy forwarding
30 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • dovecot as a component of Red Hat Enterprise Linux 10
  • dovecot-devel as a component of Red Hat Enterprise Linux 10
  • dovecot-mysql as a component of Red Hat Enterprise Linux 10
  • dovecot-pgsql as a component of Red Hat Enterprise Linux 10
  • dovecot-pigeonhole as a component of Red Hat Enterprise Linux 10
  • dovecot.src as a component of Red Hat Enterprise Linux 10
  • dovecot as a component of Red Hat Enterprise Linux 6
  • dovecot-devel as a component of Red Hat Enterprise Linux 6
  • dovecot-mysql as a component of Red Hat Enterprise Linux 6
  • dovecot-pgsql as a component of Red Hat Enterprise Linux 6
  • dovecot-pigeonhole as a component of Red Hat Enterprise Linux 6
  • dovecot.src as a component of Red Hat Enterprise Linux 6
Summary
A flaw was found in Dovecot. Forwarded information from a host listed as a trusted proxy is not properly separated from Dovecot's internal authentication fields. This allows a malicious host configured as a trusted proxy to inject values as internal authentication fields, enabling it to authenticate as any user without knowing their password. This vulnerability leads to unauthorized access and affects deployments where the password database honors a field that permits passwordless authentication.
Remediation
To mitigate this issue, ensure that the `auth_proxy_trusted_networks` configuration in Dovecot is strictly limited to only trusted hosts that are fully under administrative control. Review and restrict the `auth_proxy_trusted_networks` setting in your Dovecot configuration (e.g., `/etc/dovecot/conf.d/10-auth.conf` or similar) to prevent unauthorized hosts from acting as trusted proxies. If trusted proxies are not required, remove this configuration entirely. A restart of the Dovecot service may be required for changes to take effect.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-67673

No EUVD known-exploited evidence

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.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
4.3 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Mitigation available
01

What, why and how

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.

What

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.

Why

The affected component does not establish the requesting party's identity reliably before granting access.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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.

Why

The affected component does not establish the requesting party's identity reliably before granting access.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
an adjacent network → Improper Authentication → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Adjacent
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-287 ↗

CWE-287: Improper Authentication. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
UnauthenticatedCWE-287
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-67673Official EUVD mapping

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.

Official EUVD record
BSI · German · WID-SEC-W-2026-3076Dovecot: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Dovecot ausnutzen, um Sicherheitsvorkehrungen zu umgehen, sensible Informationen offenzulegen, Daten zu manipulieren oder Denial-of-Service-Zustände herbeizuführen.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Mitigation available
Affected
dovecot as a component of Red Hat Enterprise Linux 10; dovecot-devel as a component of Red Hat Enterprise Linux 10; dovecot-mysql as a component of Red Hat Enterprise Linux 10; dovecot-pgsql as a component of Red Hat Enterprise Linux 10; dovecot-pigeonhole as a component of Red Hat Enterprise Linux 10; dovecot.src as a component of Red Hat Enterprise Linux 10; dovecot as a component of Red Hat Enterprise Linux 6; dovecot-devel as a component of Red Hat Enterprise Linux 6; dovecot-mysql as a component of Red Hat Enterprise Linux 6; dovecot-pgsql as a component of Red Hat Enterprise Linux 6; dovecot-pigeonhole as a component of Red Hat Enterprise Linux 6; dovecot.src as a component of Red Hat Enterprise Linux 6; dovecot as a component of Red Hat Enterprise Linux 7; dovecot-devel as a component of Red Hat Enterprise Linux 7; dovecot-mysql as a component of Red Hat Enterprise Linux 7; dovecot-pgsql as a component of Red Hat Enterprise Linux 7; dovecot-pigeonhole as a component of Red Hat Enterprise Linux 7; dovecot.src as a component of Red Hat Enterprise Linux 7; dovecot as a component of Red Hat Enterprise Linux 8; dovecot-devel as a component of Red Hat Enterprise Linux 8; dovecot-mysql as a component of Red Hat Enterprise Linux 8; dovecot-pgsql as a component of Red Hat Enterprise Linux 8; dovecot-pigeonhole as a component of Red Hat Enterprise Linux 8; dovecot.src as a component of Red Hat Enterprise Linux 8; dovecot as a component of Red Hat Enterprise Linux 9; dovecot-devel as a component of Red Hat Enterprise Linux 9; dovecot-mysql as a component of Red Hat Enterprise Linux 9; dovecot-pgsql as a component of Red Hat Enterprise Linux 9; dovecot-pigeonhole as a component of Red Hat Enterprise Linux 9; dovecot.src as a component of Red Hat Enterprise Linux 9
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
To mitigate this issue, ensure that the `auth_proxy_trusted_networks` configuration in Dovecot is strictly limited to only trusted hosts that are fully under administrative control. Review and restrict the `auth_proxy_trusted_networks` setting in your Dovecot configuration (e.g., `/etc/dovecot/conf.d/10-auth.conf` or similar) to prevent unauthorized hosts from acting as trusted proxies. If trusted proxies are not required, remove this configuration entirely. A restart of the Dovecot service may be required for changes to take effect.
04

Evidence and provenance

Published 28 Aug 2026 · Last source change 28 Aug 2026, 15:54 UTC · CWE-287 · Improper Authentication

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-29
European sourceENISA EUVD · EUVD-2026-67673
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →
  1. ENISA EUVD mappingEUVD-2026-67673 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-67673"}
    ENISA EUVD ↗
  2. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-67673↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-42008 · cve.blacktree.nl