Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| authlib | authlib | affected |
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| Authlib | Authlib |
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| Source | ID | Title |
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Github GHSA |
GHSA-7vr2-2fgp-9w7p | Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.213% probability within 30 days)
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| CPEs | cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:* |
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ssvc
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threat_severity
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| First Time appeared |
Authlib
Authlib authlib |
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| Vendors & Products |
Authlib
Authlib authlib |
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| Description | 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 Authlib's 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. | |
| Title | Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys | |
| Weaknesses | CWE-184 CWE-347 |
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| References |
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| Metrics |
cvssV3_1
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