SEPTEMBER 27, 2026
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Case File

CVE-2021-29456

MEDIUM · CVSS 5.7 EPSS 0.51% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-04-21 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 5.7. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-29456
Severity
MEDIUM
CVSS
5.7
EPSS
0.51%

Original NVD 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.

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