5.8
CVSSv2

CVE-2021-32786

Published: 22/07/2021 Updated: 07/11/2023
CVSS v2 Base Score: 5.8 | Impact Score: 4.9 | Exploitability Score: 8.6
CVSS v3 Base Score: 6.1 | Impact Score: 2.7 | Exploitability Score: 2.8
VMScore: 516
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:N

Vulnerability Summary

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 before 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.

Vulnerability Trend

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openidc mod_auth_openidc

fedoraproject fedora 33

fedoraproject fedora 34

Vendor Advisories

Debian Bug report logs - #991582 libapache2-mod-auth-openidc: CVE-2021-32786 Package: src:libapache2-mod-auth-openidc; Maintainer for src:libapache2-mod-auth-openidc is Moritz Schlarb <schlarbm@uni-mainzde>; Reported by: Salvatore Bonaccorso <carnil@debianorg> Date: Tue, 27 Jul 2021 20:09:03 UTC Severity: important ...
mod_auth_openidc is an authentication/authorization module for the Apache 2x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider In versions prior to 249, `oidc_validate_redirect_url()` does not parse URLs the same way as most browsers do As a result, this function can be bypas ...