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CVE-2026-114618— Authlib: Default JWT bearer grant accepts assertions for the wrong audience

Quick assessment

Affected
authlib authlib
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Authlib 是一个用于构建 OAuth 和 OpenID Connect 服务器的 Python 库。在 1.9.0 版本之前，默认的 RFC 7523 JWTBearerGrant.get_audiences() 方法会返回一个空列表，导致 JWTBearerGrant.verify_claims() 在验证时仅要求存在 aud（受众）声明，而不会校验该声明是否与当前授权服务器匹配。攻击者若持有针对其他服务的合法断言，便可将其提交给使用相同签名密钥且采用默认授权方式的服务器，从而跨越信任边界获取访问令牌。对于

CVSS 6.8 · Medium
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I. Basic Information for CVE-2026-114618

Vulnerability Information
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Vulnerability Title
Authlib: Default JWT bearer grant accepts assertions for the wrong audience
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
authlib authlib < 1.9.0 -

II. Public POCs for CVE-2026-114618

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III. Intelligence Information for CVE-2026-114618

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Other References for CVE-2026-114618 (4)

Same Patch Batch · authlib · 2026-10-22 · 7 CVEs total

CVE-2026-114615 7.4 HIGH Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys
CVE-2026-114616 7.4 HIGH Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)
CVE-2026-114620 5.4 MEDIUM Authlib: Unvalidated request_uri fetch in JWT-secured authorization request (JAR) leading
CVE-2026-114619 4.6 MEDIUM Authlib: OpenID implicit grant checks raw scope instead of allowed scope before issuing ID
CVE-2026-114617 4.2 MEDIUM Authlib: ID token can disable its own nonce validation via the nonce_supported claim
CVE-2026-114614 2.6 LOW Authlib: is_secure_transport() loopback exemption can be bypassed with a userinfo componen

IV. Related Vulnerabilities

Same product: authlib
Same vendor: authlib
Same weakness: CWE-287

V. Comments for CVE-2026-114618

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