An issue was discovered in fastecdsa before 2.1.2.
Priority LOW 35CWE-347Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-347.
Summary
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.
Why it matters now
EPSS 0.01311 70th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed fastecdsa (PyPI): 2.1.2
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | fastecdsa (PyPI) | before 2.1.2 | 2.1.2 | Patch available | GHSA-56wv-2wr9-3h9r |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- fastecdsa (PyPI) Vendor— Affected before 2.1.2 Fixed in 2.1.2 Patch available GHSA-56wv-2wr9-3h9r
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:antonkueltz:fastecdsa:*:*:*:*:*:*:*:* | before 2.1.2 | Vulnerable | Antonkueltz |
- cpe:2.3:a:antonkueltz:fastecdsa:*:*:*:*:*:*:*:* Versions before 2.1.2 Vulnerable ·Antonkueltz
Remediation
- Fix · GHSA-56wv-2wr9-3h9r fastecdsa (PyPI) Fixed in 2.1.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2020-12607
- 2026-10-03 Alias added: GHSA-56wv-2wr9-3h9r
References
Patch 3
Advisory 2
More Antonkueltz Fastecdsa vulnerabilities
- TI-2024-14259 Use of uninitialized resource in fastecdsa CVSS 3.1HIGH 7.5
Sources
- CVE-2020-12607 · CVE Program
- CVE-2020-12607 · NVD
- FIRST EPSS
- GHSA-56wv-2wr9-3h9r · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences