CVE-2021-38195
Overflow in libsecp256k1
CVE-2021-38195 is a critical vulnerability (CVSS 9.8) in Parity Libsecp256k1, published July 13, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.91%, the 60th percentile. Fixed in libsecp256k1 0.5.0.
- Severity
- 9.8 CriticalCVSS 3.1, NVD
- Exploit chance
- 0.91%EPSS, 60th percentile
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
0.5.0libsecp256k1 +1 more
Description
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libsecp256k1crates.io | before 0.5.0 | 0.5.0 |
libsecp256k1crates.io | 0.0.0-0 up to 0.5.0 | 0.5.0 |
What each source reports
NVD Score used
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.
- Record
CVE-2021-38195- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-347
- Updated
- 2026-11-02
CVE ListNo score
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.
- Record
CVE-2021-38195- Updated
- 2026-11-02
EUVDEUVD-2021-1711No score
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.
- Record
EUVD-2021-1711- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-g4vj-x7v9-h82m
Overflow in libsecp256k1
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.
- Record
GHSA-g4vj-x7v9-h82m- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-190, CWE-347
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-38195- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
OSVGHSA-g4vj-x7v9-h82m
Overflow in libsecp256k1
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.
- Record
GHSA-g4vj-x7v9-h82m- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-190, CWE-347
- Updated
- 2026-11-02
OSVRUSTSEC-2021-0076No score
libsecp256k1 allows overflowing signatures
libsecp256k1 accepts signatures whose R or S parameter is larger than the secp256k1 curve order, which differs from other implementations. This could lead to invalid signatures being verified.
The error is resolved in 0.5.0 by adding a check_overflow flag.
- Record
RUSTSEC-2021-0076- Updated
- 2026-11-02
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD, OSV | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
References
rustsec.org/advisories/RUSTSEC-2021-0076.html
raw.githubusercontent.com/rustsec/advisory-db/main/crates/libsecp256k1/RUSTSEC-2021-0076.md
nvd.nist.gov/vuln/detail/CVE-2021-38195
github.com/paritytech/libsecp256k1/pull/67
crates.io/crates/libsecp256k1