PT-2026-27058 · Jsrsasign · Jsrsasign

Kr0Emer · Published 2026-03-23 · Updated 2026-03-23 · CVE-2026-4602

Positive Technologies (AI Summary)

CVSS v4.0

7.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Name of the Vulnerable Software and Affected Versions jsrsasign versions prior to 11.1.1

Description The software contains a flaw related to incorrect conversion between numeric types when handling negative exponents in the ext/jsbn2.js file. This can allow an attacker to force the computation of incorrect modular inverses, potentially breaking signature verification by calling the modPow function with a negative exponent.

Recommendations Update to jsrsasign version 11.1.1 or later.

Exploit

Fix

Weakness Enumeration

CWE-681

Related Identifiers

CVE-2026-4602

GHSA-8QWJ-4JXW-M8JW

Affected Products

Jsrsasign

References · 11

• 🔥 https://gist.github.com/Kr0emer/7ecd2be7d17419e4677315ef3758faf5 · Exploit
• https://github.com/kjur/jsrsasign/commit/5ea1c32bb2aa894b4bd29849839afe4f98728195 · Patch
• https://osv.dev/vulnerability/GHSA-8qwj-4jxw-m8jw · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-4602 · Security Note
• https://osv.dev/vulnerability/CVE-2026-4602 · Vendor Advisory
• https://github.com/kjur/jsrsasign/pull/650 · Note
• https://github.com/kjur/jsrsasign · Note
• https://twitter.com/CVEarity/status/2036123565326729368 · Twitter Post
• https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371175 · Note
• https://twitter.com/VulmonFeeds/status/2035970908599312589 · Twitter Post
• https://twitter.com/CVEnew/status/2035992479451816147 · Twitter Post