CVE-2026-6420
Keylime: keylime: security bypass due to hardcoded tpm quote nonce
A flaw was found in Keylime. An attacker with root access on an enrolled monitored machine, where the Keylime agent runs, can exploit a vulnerability in the Keylime verifier. The verifier uses a hardcoded challenge nonce for Trusted Platform Module (TPM) quote attestation instead of a cryptographically random value. This allows the attacker to stockpile valid TPM quotes and replay them to evade detection after compromising the system. This issue affects only the push model deployment.
Fixes and workarounds
Workaround
Primary fix (one-line change in keylime/models/verifier/evidence.py): Before (vulnerable): def generate_challenge(self, bit_length): self.challenge = Nonce.generate(bit_length) self.challenge = bytes.fromhex("49beed365aac777dae23564f5ad0ec") After (fixed): def generate_challenge(self, bit_length): self.challenge = Nonce.generate(bit_length) Existing partial mitigations (already active): 1. TPM clock monotonicity check: limits each quote to one replay. 2. Push attestation timeout (default 10s): constrains the quote generation window, but TPM throughput allows 50-200 quotes to be stockpiled in that time.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
keylime
https://github.com/keylime/keylime |
≥ 7.14.0; < 7.14.2 (affected, semver)
Other versions: unaffected |
CNA: redhat |
| Red Hat Enterprise Linux 10 Red Hat keylime
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:7.14.1-5.el10_2.1; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat keylime
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 6.3 medium |
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/errata/RHSA-2026:28582CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-6420CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2458889CNA: redhat · issue-tracking, x_refsource_REDHAT
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