CVE-2026-114615

Authlib is a Python library which builds OAuth and OpenID Connect servers. From 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlibs PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0.

Weakness

The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete.

Affected Software

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/120.html
• https://cwe.mitre.org/data/definitions/15.html
• https://cwe.mitre.org/data/definitions/182.html
• https://cwe.mitre.org/data/definitions/3.html
• https://cwe.mitre.org/data/definitions/43.html
• https://cwe.mitre.org/data/definitions/6.html
• https://cwe.mitre.org/data/definitions/71.html
• https://cwe.mitre.org/data/definitions/73.html
• https://cwe.mitre.org/data/definitions/85.html

References

• https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf
• https://github.com/authlib/authlib/pull/945
• https://github.com/authlib/authlib/releases/tag/v1.9.0
• https://github.com/authlib/authlib/security/advisories/GHSA-7vr2-2fgp-9w7p
• https://github.com/authlib/authlib/security/advisories/GHSA-7vr2-2fgp-9w7p