Improper Verification of Cryptographic Signature in fastecdsa

HOCH 7.5CVE-2020-12607 · GHSA-56wv-2wr9-3h9r · PYSEC-2020-42 · Published 02/06/2020 · updated 17/06/2026

Kurz gesagt

CVE-2020-12607 ist eine Schwachstelle (HOCH (CVSS 7.5)) in fastecdsa, fastecdsa (antonkueltz).
Wahrscheinlichkeit einer Ausnutzung in den nächsten 30 Tagen (EPSS): 1.3%, höher als bei 70.8% aller Schwachstellen.
Abhilfe: auf 2.1.2 oder neuer aktualisieren.

Package	Affected versions	Patched versions
fastecdsa PyPI	`< 2.1.2`	`2.1.2`
fastecdsa antonkueltz	`< 2.1.2`	`2.1.2`

Description

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<sup>-1</sup>, 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.

NVD description

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.

References

nvd.nist.gov/vuln/detail/CVE-2020-12607 · ADVISORY
AntonKueltz/fastecdsa · WEB
AntonKueltz/fastecdsa commit 4a16dae · WEB
AntonKueltz/fastecdsa commit 7b64e3e · WEB
AntonKueltz/fastecdsa commit e592f10 · WEB
AntonKueltz/fastecdsa · PACKAGE
GitHub Advisory GHSA-56wv-2wr9-3h9r · ADVISORY
pypa/advisory-database · WEB

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Package

Affected versions

Patched versions

fastecdsa

PyPI

< 2.1.2

2.1.2

fastecdsa

antonkueltz

< 2.1.2

2.1.2

Description

NVD description

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.