How severe is CVE-2021-3406?

CVE-2021-3406 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-3406 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3406?

CVE-2021-3406 primarily affects Keylime. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3406?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-3406 published?

CVE-2021-3406 was published on 2021-02-25 and last updated on 2026-06-17.

CVE-2021-3406

CVE-2021-3406 is a critical-severity vulnerability in Keylime with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Keylime
Published: 2021-02-25
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-3406?: CVE-2021-3406 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-3406 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3406?: CVE-2021-3406 primarily affects Keylime. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3406?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-3406 published?: CVE-2021-3406 was published on 2021-02-25 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:keylime:keylime:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

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