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Vulnerability PYSEC-2026-4358

Medium Risk

8 days ago

No summary available

0.1rc0 - 1.8.0

Details

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, the default RFC 7523 JWTBearerGrant.get_audiences() returns an empty list, causing JWTBearerGrant.verify_claims() to require only that an aud claim exists without matching the current authorization server. An attacker holding a legitimate assertion for another service can present it to a server that shares the signing key and uses the default grant, obtaining an access token across a trust boundary. Implementations that override get_audiences() with the server's valid audience identifiers are not affected. This issue is fixed in version 1.9.0.

References

Related Vulnerabilities

Other vulnerabilities affecting the same packages

Authlib RFC 7592 examples omit registration-access-token client binding

0.15 - 1.9.0 GHSA-c73q-w75p-j82v

Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

0.1rc0 - 1.9.0 GHSA-8m4g-j4wp-wgcg

Authlib: Unvalidated request_uri fetch in JWT-secured authorization request (JAR) leading to SSRF

1.6.0 - 1.8.0 GHSA-x4rv-c3wx-4cr8

Authlib: ID token can disable its own nonce validation via the nonce_supported claim

0.1rc0 - 1.8.0 GHSA-c5mf-xmp2-59rc

Authlib: Default JWT bearer grant accepts assertions for the wrong audience

0.1rc0 - 1.8.0 GHSA-fch4-3c6x-j4gc

View all vulnerabilities for these packages

Impacted packages

authlib

Timeline

Published

8 days ago

Fixed (1.9.0)

16 days ago

Last Modified

17 hours ago