CVE-2026-4599: kjur jsrsasign
Vulnerability summary
CVE-2026-4599 is a critical (CVSS 9.3) vulnerability in kjur jsrsasign. EPSS estimates a 0.81% chance of exploitation in the next 30 days, higher than 56.4% 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 from 7.0.0 and before 11.1.1 are vulnerable to Incomplete Comparison with Missing Factors via the getRandomBigIntegerZeroToMax and getRandomBigIntegerMinToMax functions in src/crypto-1.1.js; an attacker can recover the private key by exploiting the incorrect compareTo checks that accept out-of-range candidates and thus bias DSA nonces during signature generation.
CVSS metrics
6 scores · 3 sources · 2 versions- OSV · NpmEcosystem advisory · calculated9.3CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- NVDNIST9.3CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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
- OSV · NpmEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- NVDNIST9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS trend
Probability
0.81%
Chance of exploitation in the next 30 days
Percentile
56%
Versus all other CVEs
30-day change
+0.33 pp
From 0.48% on 21-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 found081681818B51605C91945126D74B4F20
Maturity: poc
Weaknesses
CWE · root cause- CWE-1023Incomplete Comparison with Missing FactorsThe product performs a comparison between entities that must consider multiple factors or characteristics of each entity, but the comparison does not include one or more of these factors.
- CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.
Affected systems
Kjur1 product
- jsrsasign≥ 7.0.0, < 11.1.1
Npm1 product
- jsrsasign≥ 7.0.0, < 11.1.1
2 vendors · 2 products
References
17 linksShow all 17 references
- github.com/kjur/jsrsasignPACKAGE