CVE-2026-4601: Kjur Jsrsasign

Critical severity, CVSS 9.1. EPSS: 0.5% chance of exploitation in the next 30 days.

Versions of the package jsrsasign before 11.1.1 are vulnerable to Missing Cryptographic Step via the KJUR.crypto.DSA.signWithMessageHash process in the DSA signing implementation. An attacker can recover the private key by forcing r or s to be zero, so the library emits an invalid signature without retrying, and then solves for x from the resulting signature.

Affected products

• Kjur Jsrsasign: before 11.1.1 (fixed in 11.1.1)

Published 2026-03-23. Last modified 2026-09-10.