Vulnerability · Published Jun 2, 2020 · Assigned by mitre

CVE-2020-12607

High 7.5

In plain English

A high-severity security flaw in the fastecdsa package (PyPI). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.3% (higher than 71% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)7.5High

Exploit odds (30 days)1.3%top 29.2% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	fastecdsa	2.1.2	GHSA-56wv-2wr9-3h9r
PyPI	fastecdsa	2.1.2	PYSEC-2020-42

Affected products (as reported)

Vendor	Product	Versions
n/a	n/a	n/a

References

https://github.com/AntonKueltz/fastecdsa/commit/4a16daeaf139be20654ef58a9fe4c79dc030458c x_refsource_CONFIRM
https://github.com/AntonKueltz/fastecdsa/issues/52 x_refsource_CONFIRM
https://github.com/AntonKueltz/fastecdsa/commit/e592f106edd5acf6dacedfab2ad16fe6c735c9d1 x_refsource_CONFIRM
https://github.com/AntonKueltz/fastecdsa/commit/7b64e3efaa806b4daaf73bb5172af3581812f8de x_refsource_CONFIRM