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CVE-2026-114617— Authlib: ID token can disable its own nonce validation via the nonce_supported claim

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， 方法会从正在验证的、不可信的 ID Token 中读取 声明；当该声明的值为 JSON 布尔值 时，该方法会将预期的 nonce 设置为 null。在隐式（implicit）或混合（hybrid）类型的依赖方（relying parties）中，或直接接受外部提供的 ID Token 的应用程序中，攻击者若获取了有效签名的 Token，即可绕过 nonce 与会话之间的绑定关系，并将

CVSS 4.2 · Medium

Possible ATT&CK Techniques 2 AI

T1550.004 · Web Session Cookie T1530.002
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I. Basic Information for CVE-2026-114617

Vulnerability Information
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Vulnerability Title
Authlib: ID token can disable its own nonce validation via the nonce_supported claim
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, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID token being validated and sets the expected nonce to null when that claim is the JSON boolean false. In implicit and hybrid relying parties, or applications that directly accept externally supplied ID tokens, an attacker with a captured validly signed token can bypass the nonce-to-session binding and replay the victim's token into an attacker-controlled session. Plain authorization code flow is not affected, and the token must still pass signature, issuer, and audience validation. OpenIDMixin.parse_id_token() trusts nonce_supported in both authlib/integrations/base_client/sync_openid.py and authlib/integrations/base_client/async_openid.py to disable the expected nonce. 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:N/UI:R/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用捕获-重放进行的认证绕过
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
authlib authlib < 1.9.0 -

II. Public POCs for CVE-2026-114617

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III. Intelligence Information for CVE-2026-114617

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Other References for CVE-2026-114617 (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-2026-114618 6.8 MEDIUM Authlib: Default JWT bearer grant accepts assertions for the wrong audience
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-2026-114614 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-294

V. Comments for CVE-2026-114617

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