CVE-2026-4602: Kjur Jsrsasign

High severity, CVSS 7.5. EPSS: 0.9% chance of exploitation in the next 30 days.

Versions of the package jsrsasign before 11.1.1 are vulnerable to Incorrect Conversion between Numeric Types due to handling negative exponents in ext/jsbn2.js. An attacker can force the computation of incorrect modular inverses and break signature verification by calling modPow with a negative exponent.

Affected products

• Kjur Jsrsasign: before 11.1.1 (fixed in 11.1.1)

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