Description
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
References10
- github.com/kjur/jsrsasign/commit/5ea1c32bb2aa894b4bd29849839afe… Patch
- gist.github.com/Kr0emer/7ecd2be7d17419e4677315ef3758faf5 ExploitMitigationThird Party Advisory
- github.com/kjur/jsrsasign/pull/650 Issue Tracking
- security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15812274
- security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371175 Third Party Advisory
- access.redhat.com/errata/RHSA-2026:19375
- access.redhat.com/errata/RHSA-2026:19409
- access.redhat.com/errata/RHSA-2026:19410
- access.redhat.com/errata/RHSA-2026:6568
- access.redhat.com/errata/RHSA-2026:6720
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 4.0
-
7.7
HIGH
Score source: CNA
CVSS: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 - EPSS — exploit probability
- 1% percentile: 44 · as of 12 November 2026
- CWE
- CWE-681
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.