CVE-2026-4601 — jsrsasign
Fix: kjur/jsrsasign@0710e39CVE-2026-4601 is a CWE-325 vulnerability in jsrsasign. A fix is available for jsrsasign — see the affected versions and patch details below.
jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-4601.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
jsrsasignnpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | jsrsasign | all versions | 11.1.1npm install jsrsasign@11.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsrsasign, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jsrsasign to 11.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-4601 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-4601 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-4601. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
IMPORTANT: A flaw in the jsrsasign library allows for private key recovery due to a missing cryptographic step in the Digital Signature Algorithm (DSA) signing process. An attacker can manipulate signature generation within the KJUR.crypto.DSA.signWithMessageHash function to force specific values, enabling the…
| Product | Fixed in | Advisory |
|---|---|---|
| Migration Toolkit for Virtualization 2.1 | migration-toolkit-virtualization/mtv-console-plugin-rhel9:1779139872 | RHSA-2026:19409 |
| Migration Toolkit for Virtualization 2.9 | migration-toolkit-virtualization/mtv-console-plugin-rhel9:1778927462 | RHSA-2026:19410 |
| Red Hat Quay 3.10 | quay/quay-rhel8:1775169155 | RHSA-2026:6912 |
| Red Hat Quay 3.12 | quay/quay-rhel8:1775253092 | RHSA-2026:6720 |
| Red Hat Quay 3.15 | quay/quay-rhel8:1775169219 | RHSA-2026:6568 |
| Red Hat Quay 3.16 | quay/quay-rhel9:1779204086 | RHSA-2026:19375 |
| Red Hat Quay 3.9 | quay/quay-rhel8:1775169218 | RHSA-2026:6926 |
Frequently Asked Questions
Is CVE-2026-4601 in your dependencies?
O3 Security finds CVE-2026-4601 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.