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Vulnerability record · CVE-2026-4600 · published 23 March 2026

CVE-2026-4600: Kjur jsrsasign improper verification of cryptographic signature vulnerability

Kjur · Jsrsasign

Versions of the package jsrsasign before 11.1.1 are vulnerable to Improper Verification of Cryptographic Signature via the DSA domain-parameter validation in KJUR.crypto.DSA.setPublic (and the related DSA/X509 verification flow in src/dsa-2.0.js). An attacker can forge DSA signatures or X.509 certificates that X509.verifySignature() accepts by supplying malicious domain parameters such as g=1, y=1, and a fixed r=1, which make the verification equation true for any hash.

8.1 CVSS 4.0 High EPSS 0.32% · top 77.5% CWE-347 · Improper verification of cryptographic signature
8.1CVSS 4.0 base score
0.32%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
16References, 2 tagged exploit
10 Sep 2026Last modified by NVD

Description

Versions of the package jsrsasign before 11.1.1 are vulnerable to Improper Verification of Cryptographic Signature via the DSA domain-parameter validation in KJUR.crypto.DSA.setPublic (and the related DSA/X509 verification flow in src/dsa-2.0.js). An attacker can forge DSA signatures or X.509 certificates that X509.verifySignature() accepts by supplying malicious domain parameters such as g=1, y=1, and a fixed r=1, which make the verification equation true for any hash.

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gist.github.com/Kr0emer/bf15ddc097176e951659a24a8e9002a7 ExploitMitigationThird Party Advisory
https://github.com/kjur/jsrsasign/commit/37b4c06b145c7bfd6bc2a6df5d0a12c56b15ef60 Patch
https://github.com/kjur/jsrsasign/pull/646 Issue Tracking
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15812268
https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370940 Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:19375
https://access.redhat.com/errata/RHSA-2026:19409
https://access.redhat.com/errata/RHSA-2026:19410
https://access.redhat.com/errata/RHSA-2026:6568
https://access.redhat.com/errata/RHSA-2026:6720
https://access.redhat.com/errata/RHSA-2026:6912
https://access.redhat.com/errata/RHSA-2026:6926
https://access.redhat.com/security/cve/CVE-2026-4600
https://bugzilla.redhat.com/show_bug.cgi?id=2450208
https://gist.github.com/Kr0emer/bf15ddc097176e951659a24a8e9002a7 ExploitMitigationThird Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4600.json

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-25898Kjur jsrsasign improper verification of cryptographic signature vulnerabilityThe package jsrsasign before 10.5.25 are vulnerable to Improper Verification of Cryptographic Signature when JWS or JWT signature with non Base64URL …EPSS 1.2%9.8CVE-2020-14967Kjur jsrsasign memory buffer overflow vulnerabilityAn issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption implementation does not detect ciphertext m…EPSS 2.3%9.8CVE-2020-14968Kjur jsrsasign memory buffer overflow vulnerabilityAn issue was discovered in the jsrsasign package before 8.0.17 for Node.js. Its RSASSA-PSS (RSA-PSS) implementation does not detect signature manipul…EPSS 2.9%9.3CVE-2026-4599Kjur jsrsasign vulnerabilityVersions of the package jsrsasign from 7.0.0 and before 11.1.1 are vulnerable to Incomplete Comparison with Missing Factors via the getRandomBigInteg…EPSS 0.78%9.1CVE-2021-30246Kjur jsrsasign improper verification of cryptographic signature vulnerabilityIn the jsrsasign package through 10.1.13 for Node.js, some invalid RSA PKCS#1 v1.5 signatures are mistakenly recognized to be valid. NOTE: there is n…EPSS 0.96%8.8CVE-2026-4601Kjur jsrsasign vulnerabilityVersions of the package jsrsasign before 11.1.1 are vulnerable to Missing Cryptographic Step via the KJUR.crypto.DSA.signWithMessageHash process in t…EPSS 0.47%7.7CVE-2026-4602Kjur jsrsasign vulnerabilityVersions of the package jsrsasign before 11.1.1 are vulnerable to Incorrect Conversion between Numeric Types due to handling negative exponents in ex…EPSS 0.88%7.7CVE-2026-4598Kjur jsrsasign vulnerabilityVersions of the package jsrsasign before 11.1.1 are vulnerable to Infinite loop via the bnModInverse function in ext/jsbn2.js when the BigInteger.mod…EPSS 0.96%

Source: NIST National Vulnerability Database (record CVE-2026-4600), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.