CVE-2026-4599
Kjur Jsrsasign 7.0.0 – 11.1.1
Raw vector
CVSS: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:XSummary
CVE-2026-4599 is a critical-severity Incomplete Comparison with Missing Factors (CWE-1023) vulnerability in Kjur Jsrsasign. Its CVSS base score is 9.3 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Forge Web Credentials (T1606); ranked at the 39th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and AC-24 (Access Control Decisions) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-4599 is an incomplete comparison vulnerability (CWE-1023) affecting versions of the jsrsasign JavaScript package from 7.0.0 up to but not including 11.1.1. The issue resides in the getRandomBigIntegerZeroToMax and getRandomBigIntegerMinToMax functions within src/crypto-1.1.js, where incorrect compareTo checks accept out-of-range candidates. This flaw leads to biased DSA nonces during signature generation, enabling private key recovery. The vulnerability carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N), indicating critical severity.
A remote, unauthenticated attacker can exploit this vulnerability by targeting applications using the affected jsrsasign versions for DSA signature generation. By leveraging the biased nonce generation, the attacker can recover the private key after observing a sufficient number of signatures, compromising confidentiality and integrity of signed data without requiring user interaction or privileges.
Advisories and patches, including the jsrsasign GitHub commit ee4b013478366cb16cea9a4bdfb218b6077f83b1 and pull request #647, address the issue by fixing the compareTo checks in the random big integer functions. Security resources like Snyk (SNYK-JS-JSRSASIGN-15370939) recommend upgrading to jsrsasign version 11.1.1 or later to mitigate the vulnerability. A proof-of-concept is available in the referenced GitHub Gist.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14373
Vulnerability Data
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…
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accept out-of-range candidates and thus bias DSA nonces during signature generation.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 3 hardening rules · 3 OS baselines
V6.3.4V6.3.5V6.1.3V6.5.7
Mitigating Controls (NIST 800-53 r5) AI
Requiring specific approved cryptography for protection directly mandates use of strong PRNGs instead of weak ones.
Mandating that access-control decisions apply the full set of required rules to each request structurally eliminates missing-factor comparisons.
Access enforcement requires that every authorization decision evaluate all relevant entity attributes, directly stopping incomplete comparisons from being used.
Engineering principles applied during design and development include selection of cryptographically strong random number generation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices (reviews, testing, static analysis) directly prevent incomplete comparison flaws from being introduced.
Authentication decisions often rely on multi-factor comparisons; incomplete comparisons directly weaken this control.
Enforcing access policy requires complete evaluation of all relevant attributes; missing factors undermine authorization decisions.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Mandates use of approved cryptographic controls, directly requiring cryptographically strong RNGs.
Security testing can detect missing comparison factors, yet testing is only one part of the control's scope.
Secure SDLC processes should catch weak PRNG usage during design and code review.
Application security requirements can mandate complete multi-factor comparisons, but the control is broader than this single weakness.
Secure architecture principles can require exhaustive entity comparisons, yet the control addresses many other design concerns.
Secure coding standards can forbid incomplete comparisons, but the control covers a wide range of coding issues.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248563 The OL 8 SSH server must be configured to use strong entropy. prevents CWE-338
RHEL 8 (1 rule)
- V-230253 RHEL 8 must ensure the SSH server uses strong entropy. prevents CWE-338
Ubuntu 22.04 (1 rule)
- V-260650 Ubuntu 22.04 LTS must implement NIST FIPS-validated cryptography to protect classified information and for the following: To provision digital signatures, to generate cryptographic hashes, and to protect unclassified information requiring confidentiality and cryptographic protection in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-338