What is CVE-2021-45451?

CVE-2021-45451 is a high-severity vulnerability in Arm Mbed TLS, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 7.5/10. Published 2021-12-21.

How severe is CVE-2021-45451?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Arm Mbed TLS

CVE-2021-45451

In Mbed TLS before 3.1.0, psa_aead_generate_nonce allows policy bypass or oracle-based decryption when the output buffer is at memory locations accessible to an untrusted application.

Vulnerability class: POODLE (CVE-2014-3566)

Published 2021-12-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.010 (60.7th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.010 · change: +0.000

Affected products

Arm Mbed TLS
Fedoraproject Fedora — versions 36, 37

Weakness classification (CWE)

CWE-327 — Use of a Broken or Risky Cryptographic Algorithm

References

github.com/ARMmbed/mbedtls/releases/tag/v3.1.0 (Patch, Third Party Advisory, Release Notes)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)

Frequently asked questions

What is CVE-2021-45451?: CVE-2021-45451 is a high-severity vulnerability in Arm Mbed TLS, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 7.5/10. Published 2021-12-21.
How severe is CVE-2021-45451?: High severity. CVSS v3 base score is 7.5 out of 10.