Authlib Vulnerability Has Left Logins Exposed
A flaw in the popular authentication library allows attackers to bypass login security checks without credentials.
Updated on Sept. 29, 2026 in Cybersecurity
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A critical vulnerability tracked as CVE-2026-96760 has been identified in the Authlib library, affecting versions up to and including 1.7.2. The security flaw allows unauthorized parties to bypass login protocols entirely without requiring valid credentials or keys.
Why it matters
The vulnerability poses a significant risk to the large ecosystem of applications relying on Authlib for identity management, as no official patch has been released to resolve the security gap.
The flaw resides in the deserialize_json function within the JSON Web Signature (JWS) component, which improperly validates tokens. The library currently treats JWS objects with empty signatures as valid by default, facilitating the authentication bypass.
The players
CERT Coordination Center
A research center at Carnegie Mellon University that tracks and coordinates responses to software vulnerabilities.
Authlib
A Python library providing tools for authentication and authorization protocols like OAuth and OpenID Connect.
The details
The vulnerability stems from how the library processes JSON Web Signatures (JWS) — a compact, URL-safe means of representing claims to be transferred between two parties. Attackers can exploit the deserialize_json function by providing a crafted payload that lacks a signature. Because the system defaults to accepting these unsigned packets, the authentication layer fails to verify identity, granting the attacker access without credentials.
Timeline
May 2026: Authlib version 1.7.2 was released.
August 30, 2026: Authlib version 1.8.0 was released.
August 2026: Authlib recorded 103.3 million downloads from PyPI.
September 29, 2026: The security advisory was published.
The Tech Race
This flaw follows the pattern of the 2021 Log4j vulnerability by highlighting systemic risks within widely used open-source dependencies. The lack of a vendor response after five weeks of attempted outreach highlights the challenges in maintaining security for critical infrastructure code.
Developers currently using Authlib versions 1.7.2 or earlier should review their authentication logic, as no official patch is currently available to mitigate this bypass. Monitoring the project's GitHub repository for future updates is the only available path for remediation at this time.
The takeaway
The security of millions of applications now depends on how quickly the maintainers provide a patch for this authentication bypass. Users should watch the project repository for the release of a security-focused version update.
Further reading
For more on how infrastructure vulnerabilities are tracked and mitigated, visit Cybersecurity.
Source note: This article includes information reported by Cybernews.
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