CVE-2021-32786

Published: 22 July 2021

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.

Priority

Cvss 3 Severity Score

6.1

Score breakdown

Status

Package	Release	Status
libapache2-mod-auth-openidc Launchpad, Ubuntu, Debian	bionic	Not vulnerable (code not present)
	focal	Not vulnerable (code not present)
	hirsute	Ignored (end of life)
	impish	Not vulnerable (2.4.9-1)
	jammy	Not vulnerable (2.4.9-1)
	kinetic	Not vulnerable (2.4.9-1)
	lunar	Not vulnerable (2.4.9-1)
	mantic	Not vulnerable (2.4.9-1)
	trusty	Does not exist
	upstream	Released (2.4.9-1)
	xenial	Needed

Severity score breakdown

Parameter	Value
Base score	6.1
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Changed
Confidentiality	Low
Integrity impact	Low
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

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