🛡️ CVE-2026-34040 — engine

🟠 CVSS 8.8 — High ✅ No Known Exploit CWE-288 NVD
8.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Moby has AuthZ plugin bypass when provided oversized request bodies

Summary

A security vulnerability has been detected that allows attackers to bypass [authorization plugins (AuthZ)](https://docs.docker.com/engine/extend/plugins_authorization/) under specific circumstances. The base likelihood of this being exploited is low.

This is an incomplete fix for [CVE-2024-41110](https://github.com/moby/moby/security/advisories/GHSA-v23v-6jw2-98fq).

Impact

If you don't use AuthZ plugins, you are not affected.

Using a specially-crafted API request, an attacker could make the Docker daemon forward the request to an authorization plugin without the body. The authorization plugin may allow a request which it would have otherwise denied if the body had been forwarded to it.

Anyone who depends on authorization plugins that introspect the request body to make access control decisions is potentially impacted.

Workarounds

If unable to update immediately:

  • Avoid using AuthZ plugins that rely on request body inspection for security decisions.
  • Restrict access to the Docker API to trusted parties, following the principle of least privilege.

Credits

  • 1seal / Oleh Konko ([@1seal](https://github.com/1seal))
  • Cody (c@wormhole.guru)
  • Asim Viladi Oglu Manizada (@manizada)

Resources

  • [CVE-2024-41110 / GHSA-v23v-6jw2-98fq](https://github.com/moby/moby/security/advisories/GHSA-v23v-6jw2-98fq)

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-34040 is classified as CWE-288: Authentication Bypass Using an Alternate Path. A secondary route into the application skips the authentication that the primary route enforces.

Affected software

CVE-2026-34040 is recorded against 5 packages.

  • engine (fixed in 29.3.1)
  • github.com/docker/docker
  • github.com/moby/moby
  • github.com/moby/moby/v2
  • moby (fixed in 29.3.1)

Timeline and source

Published on 31 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
github.com

CVE-2026-34040 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE CWE-288
Public Exploit ✅ No
Source NVD
Published 2026-03-31
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
engine — 29.3.1
github.com/docker/docker — —
github.com/moby/moby — —
github.com/moby/moby/v2 — —
moby — 29.3.1

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