{"cve":"CVE-2021-32786","nvd":{"published":"2021-07-22T22:15:08.233","modified":"2026-06-17T03:53:37.627","status":"Modified","description":"mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9, `oidc_validate_redirect_url()` does not parse URLs the same way as most browsers do. As a result, this function can be bypassed and leads to an Open Redirect vulnerability in the logout functionality. This bug has been fixed in version 2.4.9 by replacing any backslash of the URL to redirect with slashes to address a particular breaking change between the different specifications (RFC2396 / RFC3986 and WHATWG). As a workaround, this vulnerability can be mitigated by configuring `mod_auth_openidc` to only allow redirection whose destination matches a given regular expression.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-601"],"references":["https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/","https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544","https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9","https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7","https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html"],"products":["fedoraproject:fedora","openidc:mod_auth_openidc"],"source":"nvd","synced_at":"2026-10-19T21:21:13.713336758+00:00"},"epss":{"cve":"CVE-2021-32786","score":0.02364,"percentile":0.83798,"date":"2026-10-31"},"kev":null,"osv":[],"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."]}