CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NCVE-2020-12607
High (7.5) in antonkueltz fastecdsa. EPSS 1.3% chance of exploitation in the next 30 days. Fixed in fastecdsa 2.1.2.
An issue was discovered in fastecdsa before 2.1.2. When using the NIST P-256 curve in the ECDSA implementation, the point at infinity is mishandled. This means that for an extreme value in k and s^-1, the signature verification fails even if the signature is correct. This behavior is not solely a usability problem. There are some threat models where an attacker can benefit by successfully guessing users for whom signature verification will fail.
Severity
- EPSS
- 1.3% chance of exploitation in the next 30 days; higher than 70% of CVEs (scores of 2026-10-31)
- CWE
- CWE-347
- Published
- Modified
- Record from
- the NVD, synced
Affected
- antonkueltz:fastecdsa
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-56wv-2wr9-3h9r | PyPI | fastecdsa | <2.1.2 | 2.1.2 |
| PYSEC-2020-42 | PyPI | fastecdsa | <2.1.2 | 2.1.2 |
References
- https://github.com/AntonKueltz/fastecdsa/commit/4a16daeaf139be20654ef58a9fe4c79dc030458c
- https://github.com/AntonKueltz/fastecdsa/commit/7b64e3efaa806b4daaf73bb5172af3581812f8de
- https://github.com/AntonKueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1
- https://github.com/AntonKueltz/fastecdsa/issues/52
- https://github.com/AntonKueltz/fastecdsa/commit/4a16daeaf139be20654ef58a9fe4c79dc030458c