Signature Verification Bypass in jwt-simple
Priority LOW 38CWE-347Published · Updated
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
- —
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- —
- Fix status
- Fixed
No CVSS vector from any source. Fix status from GitHub. Impact type from CWE-347.
Summary
Versions of `jwt-simple` prior to 0.5.3 are vulnerable to Signature Verification Bypass. If no algorithm is specified in the `decode()` function, the packages uses the algorithm in the JWT to decode tokens. This allows an attacker to create a HS256 (symmetric algorithm) JWT with the server's public key as secret, and the package will verify it as HS256 instead of RS256 (asymmetric algorithm). ## Recommendation Upgrade to version 0.5.3 or later.
Why it matters now
Fix Fixed jwt-simple (npm): 0.5.3
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | jwt-simple (npm) | before 0.5.3 | 0.5.3 | Patch available | GHSA-8v5f-hp78-jgxq |
- jwt-simple (npm) Vendor— Affected before 0.5.3 Fixed in 0.5.3 Patch available GHSA-8v5f-hp78-jgxq
Remediation
- Fix · GHSA-8v5f-hp78-jgxq jwt-simple (npm) Fixed in 0.5.3 Advisory →
Timeline
- 2026-10-03 Threatist record created from GHSA-8v5f-hp78-jgxq
References
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences