CVE-2021-29456

Authelia allows open redirects on the logout endpoint

MEDIUM
5.4
CVSS Score
Published: April 21, 2021 at 06:50 PM UTC
Updated: June 17, 2026 at 03:47 AM UTC
1 product affected across 1 vendorAuthelia

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.5%

Description

Authelia is an open-source authentication and authorization server providing 2-factor authentication and single sign-on (SSO) for your applications via a web portal. In versions 4.27.4 and earlier, utilizing a HTTP query parameter an attacker is able to redirect users from the web application to any domain, including potentially malicious sites. This security issue does not directly impact the security of the web application itself. As a workaround, one can use a reverse proxy to strip the query parameter from the affected endpoint. There is a patch for version 4.28.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.28.0<= 4.27.4
Affected range stops below 4.28.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-601

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