How severe is CVE-2021-45696?

CVE-2021-45696 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-2021-45696 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-45696?

CVE-2021-45696 affects Sha2 Project Sha2. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-45696?

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-2021-45696 published?

CVE-2021-45696 was published on 2021-12-27 and last updated on 2026-06-17.

CVE-2021-45696

CVE-2021-45696 is a critical-severity vulnerability in Sha2 Project Sha2 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-327.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-327
Affected product: Sha2 Project Sha2
Published: 2021-12-27
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-45696?: CVE-2021-45696 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-2021-45696 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-45696?: CVE-2021-45696 affects Sha2 Project Sha2. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-45696?: 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-2021-45696 published?: CVE-2021-45696 was published on 2021-12-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:sha2_project:sha2:0.9.7:*:*:*:*:rust:*:*

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