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Reflected XSS in SFE

Critical
BeryJu published GHSA-pgff-5mx8-fqj3 May 12, 2026

Package

authentik

Affected versions

<= 2026.2.2
<= 2025.12.4

Patched versions

2026.2.3
2025.12.5

Description

Summary

Due to the implementation of stages in the SFE (Simple Flow Executor) in order to make the interface more compatible with legacy browsers, it was possible to use an XSS exploit in the AutosubmitStage.

Patches

authentik 2025.12.5 and 2026.2.3 fix this issue.

Impact

The SFE (Simple Flow Executor) was susceptible to an XSS exploit. This could allow an attacker to redirect web requests containing tokens, hijack the session or take other malicious actions.

This is possible when an OAuth2 provider is configured, either through the redirect_uri when a very broad regex is used, or through the state value.

The SFE previously used jQuery without explicit sanitization, which, compared to the rest of our interfaces, did not sufficiently protect from malicious input values.

For more information

If you have any questions or comments about this advisory:

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

CVE ID

CVE-2026-42849

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

Credits