---
title: "CVE-2026-42008\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2026-42008?format=md
keywords: index, follow
---

# CVE-2026-42008

Publication date 28 August 2026

Last updated 10 September 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**4.3 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2026-42008?format=md#impact-score)

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## 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.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| dovecot | 26.04 LTS resolute | Needs evaluation |
| 24.04 LTS noble | Needs evaluation |
| 22.04 LTS jammy | Needs evaluation |
| 20.04 LTS focal | Needs evaluation |
| 18.04 LTS bionic | Needs evaluation |
| 16.04 LTS xenial | Needs evaluation |
| 14.04 LTS trusty | Needs evaluation |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2026-42008?format=md#patch-details)

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| dovecot | * Upstream:   [ae95db1](http://github.com/dovecot/core/commit/ae95db16edbc9c671ca75ec43f9ef854415b3778) * Upstream:   [ca55238](http://github.com/dovecot/core/commit/ca55238f3716da3f1df945616c12690e1919c10a) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

4.3 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Adjacent |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | Low |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 4.3 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-42008)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-42008)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-42008)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-42008)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-42008>