CVE-2026-34040
Published: 31 March 2026
Summary
CVE-2026-34040 is a high-severity Authentication Bypass Using an Alternate Path or Channel (CWE-288) vulnerability in Docker Engine. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 5.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-25 (Reference Monitor) and AC-3 (Access Enforcement).
Deeper analysis
CVE-2026-34040 is a security vulnerability in Moby, an open source container framework, affecting versions prior to 29.3.1. The flaw allows attackers to bypass authorization plugins (AuthZ), classified under CWE-288 (Authentication Bypass Using an Alternate Path or Channel). It carries a CVSS v3.1 base score of 8.8 (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H), indicating high severity due to its potential for significant impact across confidentiality, integrity, and availability with a changed scope.
A local attacker with low privileges can exploit this vulnerability with low complexity and no user interaction required. Successful exploitation enables bypassing AuthZ controls, potentially granting unauthorized access to container resources and leading to high-impact outcomes such as data exfiltration, modification of critical files, or disruption of container operations.
The issue has been patched in Moby version 29.3.1, as detailed in the official release notes and security advisory. Security practitioners should update to this version or later to mitigate the risk, with further technical details available in the GitHub advisory (GHSA-x744-4wpc-v9h2) and release tag (docker-v29.3.1).
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17289
Vulnerability details
Moby is an open source container framework. Prior to version 29.3.1, a security vulnerability has been detected that allows attackers to bypass authorization plugins (AuthZ). This issue has been patched in version 29.3.1.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The vulnerability is an authentication bypass in Moby's AuthZ plugins allowing low-privileged local attackers to gain unauthorized access to container resources and perform high-impact actions, directly enabling exploitation for privilege escalation.
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires timely identification, reporting, and patching of flaws like the AuthZ bypass in Moby prior to version 29.3.1.
Mandates enforcement of approved authorizations for access to system resources, directly countering the authorization plugin bypass.
Implements a tamperproof reference monitor to enforce access control policies, mitigating the alternate path used to bypass AuthZ plugins.