jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.8 · 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 · score source

EPSS

• CVE-2026-4601: 0.30% estimated exploitation activity in the next 30 days; percentile 23.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

23 Mar 2026, 06:30 UTC

Last modified by the source

29 Mar 2026, 16:11 UTC

Source last checked

26 Oct 2026, 12:47 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-w8q8-93cx-6h7r

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-w8q8-93cx-6h7r

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# Patch Next advisory brief: CVE-2026-4601

Advisory: jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction
IDs: CVE-2026-4601, GHSA-w8q8-93cx-6h7r
Record: https://patchnext.com/advisories/cve-2026-4601 (revision 3, source checked 26 Oct 2026, 12:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: jsrsasign 11.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm jsrsasign: affected < 11.1.1; fixed in 11.1.1

## Suggested inspection (read-only)
- `npm ls jsrsasign --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on jsrsasign.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-w8q8-93cx-6h7r (OSV record GHSA-w8q8-93cx-6h7r lists affected ranges: npm jsrsasign >=0 <11.1.1 (fixed))
- Verified: https://github.com/advisories/GHSA-w8q8-93cx-6h7r (GitHub-reviewed advisory GHSA-w8q8-93cx-6h7r lists affected ranges: npm jsrsasign >=0 <11.1.1)

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