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Fencer Intel
critical 9.8

CVE-2021-38195 json

Overflow in libsecp256k1

published 5y ago modified 4mo ago also GHSA-g4vj-x7v9-h82m , RUSTSEC-2021-0076 , EUVD-2021-1711

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

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.

Patch / fix

  • crates.io libsecp256k1 0.5.0
  • parity libsecp256k1 0.5.0

Is CVE-2021-38195 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.91% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • rustsec.org https://rustsec.org/advisories/RUSTSEC-2021-0076.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
crates.io libsecp256k1
<0.5.0
>=0.0.0-0, <0.5.0
0.5.0

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.