Cyber Resilience

CVE-2021-3505

MediumPublic PoC

Published: 19 April 2021

Published
19 April 2021
Modified
21 November 2024
KEV Added
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Patch
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CVSS Score v3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS Score 0.0013 31.5th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-3505 is a medium-severity Insufficient Entropy (CWE-331) vulnerability in Libtpms Project Libtpms. Its CVSS base score is 5.5 (Medium).

Operationally, ranked at the 31.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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(),…

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which is called before the prime number check. The highest threat from this vulnerability is to data confidentiality.

CWE(s)
CWE-331

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

libtpms project
libtpms
≤ 0.8.0
redhat
enterprise linux
8.0
fedoraproject
fedora
33

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-12 Cryptographic Key Establishment and Management
addresses: CWE-331

Approved key-establishment methods mandate sufficient entropy during key generation, eliminating entropy-starved keys.

References