{"cve":"CVE-2021-29456","nvd":{"published":"2021-04-21T19:15:35.827","modified":"2026-06-17T03:47:40.713","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","score":5.4},"cwes":["CWE-601"],"references":["https://github.com/authelia/authelia/security/advisories/GHSA-36f2-fcrx-fp4j","https://github.com/authelia/authelia/security/advisories/GHSA-36f2-fcrx-fp4j"],"products":["authelia:authelia"],"source":"nvd","synced_at":"2026-10-19T21:17:01.373894544+00:00"},"epss":{"cve":"CVE-2021-29456","score":0.0051,"percentile":0.43523,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-36f2-fcrx-fp4j","url":"https://osv.dev/vulnerability/GHSA-36f2-fcrx-fp4j","summary":"Authelia allows open redirects on the logout endpoint","modified":"2026-07-08T06:27:26.816887269Z","packages":[{"ecosystem":"Go","name":"github.com/authelia/authelia/v4","purl":"pkg:golang/github.com/authelia/authelia/v4","ranges":["<4.28.0"],"fixed":["4.28.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}