VU#762428: Authlib library contains a signature‑verification bypass vulnerability
CERT/CC has published a new security advisory. Here is a summary and what to do.
Key points
- New advisory from CERT/CC.
- Review affected versions in the advisory.
- Apply updates promptly.
CERT/CC published a security advisory titled “VU#762428: Authlib library contains a signature‑verification bypass vulnerability”.
At a glance
- Publisher
- CERT/CC
- CVEs
- See advisory
What the advisory says
Overview Authlib (versions up to and including 1.7.2) contain a signature‑verification bypass in the JSON Web Signature (JWS) general JSON serialization handling. The JsonWebSignature.deserialize_json() function accepts a JWS object with an empty "signatures" array and treats the payload as successfully verified, allowing attackers to supply arbitrary forged content without possessing any key material. Description Authlib is a Python library that provides tools for implementing OAuth, OpenID Connect, JWT/JWS/JWE (JSON Web Token / JSON Web Signature / JSON Web Encryption), and other modern authentication and authorization standards. It’s widely used in web applications and microservices to handle token creation, cryptographic validation, and secure communication. As discussed in CVE-2026-96760 , a security flaw in Authlib’s handling of JSON Web Signatures (JWS) makes it possible for an at
What should you do?
- Read the full vendor advisory linked below and confirm whether you run affected versions.
- Schedule the recommended update, prioritising internet-facing systems.
- Watch for exploitation reports; unpatched edge devices are frequent targets.
What to do and how to stay safe: CERT/CC
- Patch scores alone ignore context like network exposure and asset criticality.
- You must map vulnerabilities to specific business risks to prioritize correctly.
- Continuous exposure data replaces static scanning for accurate prioritization.
Prioritize vulnerabilities by actual exploitability and business impact, not by theoretical severity scores. Update your asset context and exposure data continuously to maintain accurate risk rankings.
Step-by-step guide: Risk Based Vulnerability Management: Prioritize Fixes by Actual Threat
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
