GHSA-mj4x-wcxf-hm8x is a medium-severity (CVSS 5.3) CWE-347 vulnerability in json-jwt. O3 Security confirms whether GHSA-mj4x-wcxf-hm8x is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Json-jwt did not verify the cryptographic signature for data
Real-World Exposure
json-jwtReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
The json-jwt rubygem version >= 0.5.0 && < 1.9.4 contains a CWE-347: Improper Verification of Cryptographic Signature vulnerability in Decryption of AES-GCM encrypted JSON Web Tokens that can result in Attacker can forge a authentication tag. This attack appear to be exploitable via network connectivity. This vulnerability appears to have been fixed in 1.9.4 and later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | json-jwt | ≥ 0.5.1&&< 1.9.4 | 1.9.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for json-jwt. 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 json-jwt to 1.9.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mj4x-wcxf-hm8x 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-mj4x-wcxf-hm8x 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-mj4x-wcxf-hm8x. 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-mj4x-wcxf-hm8x in your dependencies?
O3 detects GHSA-mj4x-wcxf-hm8x across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.