Cross-site scripting in authentik - CVE-2026-42849
Published: May 12, 2026
Vulnerability identifier: #VU131245
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2026-42849
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform cross-site scripting and hijack the session.
The vulnerability exists due to cross-site scripting in the AutosubmitStage in the SFE (Simple Flow Executor) when handling malicious input values in OAuth2 provider parameters. A remote attacker can supply a crafted redirect_uri or state value to perform cross-site scripting and hijack the session.
User interaction is required, and exploitation is possible when an OAuth2 provider is configured.
Affected software
authentik
How to mitigate CVE-2026-42849
Install security update from vendor's website.
authentik - addressed in versions 2025.12.5, 2026.2.3