CVE-2026-114617

4.2 MEDIUM 0.3% exploit odds Fix listed Auth & access Library

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-10-22 22:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-29 14:51 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 4.2 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-22 22:18 UTC
Last modified: 2026-10-29 14:51 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-294
Record status: Analyzed

Affected

Authlib < 1.9.0

Attack profile CVSS 3.1 · 4.2

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: Required
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Is it in your code?

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Fix and advisories

References

NVD record · CVE.org record