vulnerability
Ubuntu: (CVE-2021-39191): libapache2-mod-auth-openidc vulnerability
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 6 | (AV:N/AC:M/Au:N/C:P/I:P/A:N) | Sep 3, 2021 | Jun 26, 2025 | Aug 18, 2025 |
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 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the `target_link_uri` parameter. A patch in version 2.4.9.4 made it so that the `OIDCRedirectURLsAllowed` setting must be applied to the `target_link_uri` parameter. There are no known workarounds aside from upgrading to a patched version.
Solution
References
- CVE-2021-39191
- https://attackerkb.com/topics/CVE-2021-39191
- CWE-601
- URL-https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d
- URL-https://github.com/zmartzone/mod_auth_openidc/issues/672
- URL-https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4
- URL-https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2
- URL-https://www.cve.org/CVERecord?id=CVE-2021-39191
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