Not Using an Unpredictable IV with CBC Mode in keylime - CVE-2026-6420
Published: May 7, 2026
Vulnerability identifier: #VU130492
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-6420
CWE-ID: CWE-329
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Keylime
Affected software:
keylime
keylime
Detailed vulnerability description
The vulnerability allows a local privileged user to bypass attestation freshness checks via replay attacks.
The vulnerability exists due to generation of a predictable nonce in CertificationParameters.generate_challenge() when generating attestation challenges in the push attestation protocol. A local privileged user can replay previously captured valid TPM quotes to bypass attestation freshness checks via replay attacks.
The issue is limited to a single enrolled agent node, and the pull-mode attestation path is not affected.
How to mitigate CVE-2026-6420
Install security update from vendor's website.