GHSA-3fvg-4v2m-98jf
HIGHJWS and JWT signature validation vulnerability with special characters
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.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
jsrsasignnpmDescription
Impact
Jsrsasign supports JWS(JSON Web Signatures) and JWT(JSON Web Token) validation. However JWS or JWT signature with non Base64URL encoding special characters or number escaped characters may be validated as valid by mistake.
For example, even if a string of non Base64URL encoding characters such as !@$% or \11 is inserted into a valid JWS or JWT signature value string, it will still be a valid JWS or JWT signature by mistake.
When jsrsasign's JWS or JWT validation is used in OpenID connect or OAuth2, this vulnerability will affect to authentication or authorization.
By our internal assessment, CVSS 3.1 score will be 8.6. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Patches
Users validate JWS or JWT signatures should upgrade to 10.5.25.
Workarounds
Validate JWS or JWT signature if it has Base64URL and dot safe string before executing JWS.verify() or JWS.verifyJWT() method.
ACKNOWLEDGEMENT
Thanks to Adi Malyanker and Or David for this vulnerability report. Also thanks for Snyk security team for this coordination.
References
https://github.com/kjur/jsrsasign/releases/tag/10.5.25 https://github.com/kjur/jsrsasign/security/advisories/GHSA-3fvg-4v2m-98jf kjur's advisories https://github.com/advisories/GHSA-3fvg-4v2m-98jf github advisories https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-25898 https://kjur.github.io/jsrsasign/api/symbols/KJUR.jws.JWS.html#.verifyJWT https://kjur.github.io/jsrsasign/api/symbols/KJUR.jws.JWS.html#.verify https://kjur.github.io/jsrsasign/api/symbols/global__.html#.isBase64URLDot https://github.com/kjur/jsrsasign/wiki/Tutorial-for-JWS-verification https://github.com/kjur/jsrsasign/wiki/Tutorial-for-JWT-verification https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-2869122
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | jsrsasign | ≥ 4.8.0&&< 10.5.25 | 10.5.25 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
The package jsrsasign before 10.5.25 are vulnerable to Improper Verifica…
The package jsrsasign before 10.5.25 are vulnerable to Improper Verifica…
The package jsrsasign before 10.5.25 are vulnerable to Improper Verifica…
The package jsrsasign before 10.5.25 are vulnerable to Improper Verifica…
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 10.5.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3fvg-4v2m-98jf 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-3fvg-4v2m-98jf 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-3fvg-4v2m-98jf. 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-3fvg-4v2m-98jf in your dependencies?
O3 detects GHSA-3fvg-4v2m-98jf across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.