CVE-2026-6420 affects Keylime by allowing a security bypass due to the use of a hardcoded TPM quote nonce. This nonce is intended to ensure freshness and prevent replay attacks during TPM quote verification. Hardcoding it undermines the security guarantees of the attestation process. Red Hat has released an update for Keylime in Red Hat Enterprise Linux 10 to fix this issue, as detailed in advisory RHSA-2026:28582.

The vulnerability allows an attacker to bypass security controls in Keylime's TPM attestation process by exploiting the hardcoded nonce, potentially compromising the integrity verification of remote boot and runtime measurements. This could reduce the trustworthiness of the attestation mechanism, impacting systems relying on Keylime for security assurance.

Red Hat has released an official security update for Keylime in Red Hat Enterprise Linux 10 to address this vulnerability. Users should apply the update as described in Red Hat advisory RHSA-2026:28582 and the referenced article https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the vendor-provided fix.