Unauthenticated open redirect via pre-validation scope error
Published May 27, 2026 · Updated May 27, 2026
Open redirect in Authlib before 1.6.12 and in 1.7.0 allows remote attackers to redirect browsers via crafted OIDC requests. OpenIDImplicitGrant and OpenIDHybridGrant check for the openid scope before validating redirect_uri, then pass the raw value into InvalidScopeError; OAuth2Error renders it as a 302 Location. The affected OIDC provider must register an Implicit or Hybrid grant, and victim interaction is required; the flaw directly exposes no tokens or authorization codes.
Summary
What happened
Open redirect in Authlib before 1.6.12 and in 1.7.0 allows remote attackers to redirect browsers via crafted OIDC requests. OpenIDImplicitGrant and OpenIDHybridGrant check for the openid scope before validating redirect_uri, then pass the raw value into InvalidScopeError; OAuth2Error renders it as a 302 Location. The affected OIDC provider must register an Implicit or Hybrid grant, and victim interaction is required; the flaw directly exposes no tokens or authorization codes.
The record
- CVE
- CVE-2026-44681
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- Authlib
- Product
- Authlib
- Classifications
- CWE-863, CWE-601, T1204.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.6.12
- Affected versionversion=>= 1.7.0, < 1.7.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-r95x-qfjj-fjj2 request demonstrationproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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