PT-2026-27059 · Jsrsasign · Jsrsasign

Kr0Emer · Published 2026-03-23 · Updated 2026-03-23 · CVE-2026-4603

Mitre

CVSS v3.1

5.9

Medium

AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Versions of the package jsrsasign before 11.1.1 are vulnerable to Division by zero due to the RSASetPublic/KEYUTIL parsing path in ext/rsa.js and the BigInteger.modPowInt reduction logic in ext/jsbn.js. An attacker can force RSA public-key operations (e.g., verify and encryption) to collapse to deterministic zero outputs and hide “invalid key” errors by supplying a JWK whose modulus decodes to zero.

Exploit

Fix

Divide By Zero

Weakness Enumeration

CWE-369

Related Identifiers

CVE-2026-4603

Affected Products

Jsrsasign

References · 6

• 🔥 https://gist.github.com/Kr0emer/5366b7364c4fbf7e754bc377f321e9f3 · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-4603 · Security Note
• https://github.com/kjur/jsrsasign/commit/dc41d49fac4297e7a737a3ef8ebd0aa9c49ef93f · Patch
• https://github.com/kjur/jsrsasign/pull/649 · Note
• https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371176 · Note
• https://twitter.com/CVEnew/status/2035992475618181519 · Twitter Post