What is CVE-2021-45696?

CVE-2021-45696 is a critical-severity vulnerability in Sha2 Project, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 9.8/10. Published 2021-12-27.

How severe is CVE-2021-45696?

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

Vulnerability in Sha2 Project

CVE-2021-45696

An issue was discovered in the sha2 crate 0.9.7 before 0.9.8 for Rust. Hashes of long messages may be incorrect when the AVX2-accelerated backend is used.

Vulnerability class: POODLE (CVE-2014-3566)

Published 2021-12-27 · 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: 0.008 (55.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Sha2 Project — versions 0.9.7

Weakness classification (CWE)

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

References

rustsec.org/advisories/RUSTSEC-2021-0100.html (Third Party Advisory)
raw.githubusercontent.com/rustsec/advisory-db/main/crates/sha2/RUSTSEC-2021-010… (Third Party Advisory)

Frequently asked questions

What is CVE-2021-45696?: CVE-2021-45696 is a critical-severity vulnerability in Sha2 Project, classified under Use of a Broken or Risky Cryptographic Algorithm. CVSS score: 9.8/10. Published 2021-12-27.
How severe is CVE-2021-45696?: Critical severity. CVSS v3 base score is 9.8 out of 10.