GHSA-xxxq-chmp-67g4
CRITICALGHSA-xxxq-chmp-67g4 is a critical-severity (CVSS 9.8) Buffer Overflow vulnerability in jsrsasign. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-xxxq-chmp-67g4 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign
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
Impact
Jsrsasign supports RSA PKCS#1 v1.5 (i.e. RSAES-PKCS1-v1_5) and RSA-OAEP encryption and decryption. Its encrypted message is represented as BigInteger. When there is a valid encrypted message, a crafted message with prepending zeros can be decrypted by this vulnerability.
- If you don't use RSA PKCS1-v1_5 or RSA-OAEP decryption, this vulnerability is not affected.
- Risk to forge contents of encrypted message is very low.
- Risk to raise memory corruption is low since jsrsasign uses BigInteger class.
Patches
Users using RSA PKCS1-v1_5 or RSA-OAEP decryption should upgrade to 8.0.18.
Workarounds
Reject RSA PKCS1-v1_5 or RSA-OAEP encrypted message with unnecessary prepending zeros.
References
https://nvd.nist.gov/vuln/detail/CVE-2020-14967 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14967 https://vuldb.com/?id.157124 https://kjur.github.io/jsrsasign/api/symbols/KJUR.crypto.Cipher.html#.decrypt https://github.com/kjur/jsrsasign/issues/439
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | jsrsasign | all versions | 8.0.18 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsrsasign. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update jsrsasign to 8.0.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xxxq-chmp-67g4 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 pinpoints whether GHSA-xxxq-chmp-67g4 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-xxxq-chmp-67g4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-xxxq-chmp-67g4 in your dependencies?
O3 detects GHSA-xxxq-chmp-67g4 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.