CVE-2021-32786

Name	CVE-2021-32786
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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-3409-1
Debian Bugs	991582

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libapache2-mod-auth-openidc (PTS)	jessie, jessie (lts)	1.6.0-1+deb8u3	vulnerable
	stretch (security), stretch (lts), stretch	2.1.6-1+deb9u1	vulnerable
	buster	2.3.10.2-1+deb10u1	vulnerable
	buster (security)	2.3.10.2-1+deb10u4	fixed
	bullseye (security), bullseye	2.4.9.4-0+deb11u3	fixed
	bookworm	2.4.12.3-2	fixed
	sid, trixie	2.4.15.7-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libapache2-mod-auth-openidc	source	jessie	(unfixed)	end-of-life
libapache2-mod-auth-openidc	source	buster	2.3.10.2-1+deb10u2		DLA-3409-1
libapache2-mod-auth-openidc	source	(unstable)	2.4.9-1			991582

Notes

[stretch] - libapache2-mod-auth-openidc <no-dsa> (Minor issue)
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7
https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544 (v2.4.9)