CVE-2021-3505

Name: CVE-2021-3505
Creator: NVD / NIST
Published: 2021-04-19T21:15:13.27+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.40%

Last modified Jun 17, 2026

CVE-2021-3505 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. A flaw was found in libtpms in versions before 0.8.0. The TPM 2 implementation returns 2048 bit keys with ~1984 bit strength due to a bug in the TCG specification. EPSS estimates a 0.40% chance of exploitation in the next 30 days.

Description

A flaw was found in libtpms in versions before 0.8.0. The TPM 2 implementation returns 2048 bit keys with ~1984 bit strength due to a bug in the TCG specification. The bug is in the key creation algorithm in RsaAdjustPrimeCandidate(), which is called before the prime number check. The highest threat from this vulnerability is to data confidentiality.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

0.40%

32.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-331

Affected Software

Vendor	Product	Versions
Libtpms Project	Libtpms	< 0.8.0
Redhat	Enterprise Linux	8.0
Fedoraproject	Fedora	33

References

https://bugzilla.redhat.com/show_bug.cgi?id=1950046Issue Tracking, Patch, Third Party Advisory
https://github.com/stefanberger/libtpms/issues/183Exploit, Patch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NUCZX4S53TUNTSGTCRDNOQZV2V2RI4RJ/
https://bugzilla.redhat.com/show_bug.cgi?id=1950046Issue Tracking, Patch, Third Party Advisory
https://github.com/stefanberger/libtpms/issues/183Exploit, Patch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NUCZX4S53TUNTSGTCRDNOQZV2V2RI4RJ/

Timeline

Published: Apr 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3505?

How severe is CVE-2021-3505?

CVE-2021-3505 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3505?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3505?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST