What is CVE-2021-3406?

CVE-2021-3406 is a critical-severity vulnerability in Keylime, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2021-02-25.

How severe is CVE-2021-3406?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Keylime

CVE-2021-3406

A flaw was found in keylime 5.8.1 and older. The issue in the Keylime agent and registrar code invalidates the cryptographic chain of trust from the Endorsement Key certificate to agent attestations.

Published 2021-02-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (49.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Keylime
Fedoraproject Fedora — versions 34
Keylime — versions 5.8.1 and older

Weakness classification (CWE)

References

bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)
github.com/keylime/keylime/security/advisories/GHSA-78f8-6c68-375m (Third Party Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)

Frequently asked questions

What is CVE-2021-3406?: CVE-2021-3406 is a critical-severity vulnerability in Keylime, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2021-02-25.
How severe is CVE-2021-3406?: Critical severity. CVSS v3 base score is 9.8 out of 10.