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SourceStage bypass via empty POST

Critical
rissson published GHSA-xp7f-xjjx-gwm8 May 28, 2026

Package

authentik

Affected versions

<=2025.12.5
<=2026.2.3
<=2026.5.0

Patched versions

2025.12.6
2026.2.4
2026.5.1

Description

Summary

The Source stage can be bypassed by sending an empty POST.

Impact

If a Source stage is bound to a flow and the source exposes a ui_login_button and an attacker can reach the Source stage, they can bypass that stage, effectively skipping authentication at that source.

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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:N/S:U/C:H/I:H/A:H

CVE ID

CVE-2026-49448

Weaknesses

No CWEs