Auth bypass in Authlib

CVE-2026-44681

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.6.12 and 1.7.1, an unauthenticated open redirect in Authlib's OpenIDImplicitGrant and OpenIDHybridGrant authorization endpoint lets a remote attacker cause the authorization server to issue an HTTP 302 to an attacker-chosen URL by submitting an authorization request that omits the openid scope. This vulnerability is fixed in 1.6.12 and 1.7.1.

Vulnerability class: Open Redirect

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (19.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-44681: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.000

Affected products

  • Authlib — versions >= 1.7.0, < 1.7.1, < 1.6.12, 1.7.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-44681?
CVE-2026-44681 is a medium-severity vulnerability in Authlib, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-05-27.
How severe is CVE-2026-44681?
Medium severity. CVSS v3 base score is 6.1 out of 10.