CVE-2026-4602: kjur jsrsasign
Vulnerability summary
CVE-2026-4602 is a high (CVSS 8.7) vulnerability in kjur jsrsasign. EPSS estimates a 0.88% chance of exploitation in the next 30 days, higher than 58.3% of scored vulnerabilities. 1 public exploit is recorded.
Timeline
- 23-03-2026PublishedVulnerability first disclosed.
- 10-09-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
6 scores · 3 sources · 2 versions- OSV · NpmEcosystem advisory · calculated8.7HighCVSS: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
- NVDNIST7.7HighCVSS: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:XDiffers
- OSV · NpmEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.88%
Chance of exploitation in the next 30 days
Percentile
58%
Versus all other CVEs
30-day change
+0.39 pp
From 0.49% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 found7Ecd2Be7D17419E4677315Ef3758Faf5
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Kjur1 product
- jsrsasign< 11.1.1
Npm1 product
- jsrsasign< 11.1.1
2 vendors · 2 products
References
17 linksShow all 17 references
- github.com/kjur/jsrsasignPACKAGE