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9.1
CVE-2026-102946: joserfc library may accept unauthenticated messages
CVE-2026-102946 · published today
Summary
The joserfc Python library (versions before 1.7.4) can treat a specially crafted JSON message with no signatures as valid. This means an attacker could send data that the application believes is trusted, even without a signing key. Upgrade to version 1.7.4 or later to stop this behavior.
What to do
The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.
Affected software
| Vendor | Product | Affected versions |
|---|---|---|
| authlib | joserfc | < 1.7.4 |
Original advisory text
joserfc: JWS signature verification bypass via empty signatures array in jws.deserialize_json
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.4, joserfc.jws.deserialize_json() accepts a JWS General JSON Serialization with an empty signatures array as authenticated. The verify_general_json() loop performs no iterations for the empty array and returns success because no signature check failed, allowing an attacker without a signing key to supply an arbitrary payload that relying applications may treat as authentic. The issue affects the General JSON Serialization path; compact JWS and JWT decoding, Flattened JSON serialization, and JWE JSON processing do not follow this vulnerable path. This issue is fixed in version 1.7.4.
References
- https://github.com/authlib/joserfc/commit/f409f8f058225d7686acab6546c94593e4c1bf... x_refsource_MISC
- https://github.com/authlib/joserfc/releases/tag/1.7.4 x_refsource_MISC
- https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2 x_refsource_CONFIRM
Internet-facing
3 days
Internal
60 days
- Not known to be exploited
- Can be exploited automatically (estimated)
- Gives an attacker full control (estimated)
Type
CWE-290Authentication Bypass by Spoofing
CWE-345Insufficient Verification of Data Authenticity
CWE-347Improper Verification of Cryptographic Signature
Timeline
Published15 Oct 2026
Updated15 Oct 2026
First seen15 Oct 2026
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