What is CVE-2021-38195?

CVE-2021-38195 is a critical-severity vulnerability in Parity Libsecp256k1, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2021-08-08.

How severe is CVE-2021-38195?

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

Vulnerability in Parity Libsecp256k1

CVE-2021-38195

An issue was discovered in the libsecp256k1 crate before 0.5.0 for Rust. It can verify an invalid signature because it allows the R or S parameter to be larger than the curve order, aka an overflow.

Published 2021-08-08 · 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: 0.009 (59.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 59.2% 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: 0.009 · change: 0.000

Affected products

Parity Libsecp256k1

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

rustsec.org/advisories/RUSTSEC-2021-0076.html (Exploit, Patch, Third Party Advisory, Issue Tracking)
raw.githubusercontent.com/rustsec/advisory-db/main/crates/libsecp256k1/RUSTSEC-… (Third Party Advisory)

Frequently asked questions

What is CVE-2021-38195?: CVE-2021-38195 is a critical-severity vulnerability in Parity Libsecp256k1, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2021-08-08.
How severe is CVE-2021-38195?: Critical severity. CVSS v3 base score is 9.8 out of 10.