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Vulnerability record · CVE-2026-4601 · published 23 March 2026

CVE-2026-4601: Kjur jsrsasign vulnerability

Kjur · Jsrsasign

Versions of the package jsrsasign before 11.1.1 are vulnerable to Missing Cryptographic Step via the KJUR.crypto.DSA.signWithMessageHash process in the DSA signing implementation. An attacker can recover the private key by forcing r or s to be zero, so the library emits an invalid signature without retrying, and then solves for x from the resulting signature.

8.8 CVSS 4.0 High EPSS 0.47% · top 62.2% CWE-325 · CWE-325
8.8CVSS 4.0 base score
0.47%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
15References, 1 tagged exploit
10 Sep 2026Last modified by NVD

Description

Versions of the package jsrsasign before 11.1.1 are vulnerable to Missing Cryptographic Step via the KJUR.crypto.DSA.signWithMessageHash process in the DSA signing implementation. An attacker can recover the private key by forcing r or s to be zero, so the library emits an invalid signature without retrying, and then solves for x from the resulting signature.

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:H/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/93789fe6efe5519db9692d4ad1dad586 ExploitMitigationThird Party Advisory
https://github.com/kjur/jsrsasign/commit/0710e392ec35de697ce11e4219c988ba2b5fe0eb Patch
https://github.com/kjur/jsrsasign/pull/645 Issue Tracking
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-15812269
https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370941 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-2026-4601
https://bugzilla.redhat.com/show_bug.cgi?id=2450209
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4601.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%8.1CVE-2026-4600Kjur jsrsasign improper verification of cryptographic signature vulnerabilityVersions of the package jsrsasign before 11.1.1 are vulnerable to Improper Verification of Cryptographic Signature via the DSA domain-parameter valid…EPSS 0.32%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-2026-4601), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.