CVE-2026-4602

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

jsrsasign · org.webjars.npm:jsrsasign

CVSS v4.0 SNYK

7.7 HIGHCVSS:4.0/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

CVSS v4.0 GitHub

7.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

CVSS v3.1 CNA

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 SNYK

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.88% chance of exploitation in the next 30 days, 58th percentile

Published

2026-03-23

Updated

2026-09-10

Proof-of-concept exploits (1)

• https://gist.github.com/Kr0emer/7ecd2be7d17419e4677315ef3758faf5

Security advisories

• https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371175
• advisories/GHSA-8qwj-4jxw-m8jw
• kjur/jsrsasign/pull/650

References

• CVE Record
• NVD entry