CVE-2021-32786

Open Redirect in oidc_validate_redirect_url()

Severity Score

6.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

mod_auth_openidc es un módulo de autenticación/autorización para el servidor HTTP Apache versión 2.x que funciona como un OpenID Connect Relying Party, autenticando a usuarios contra un OpenID Connect Provider. En versiones anteriores a 2.4.9, "oidc_validate_redirect_url()" no analiza las URLs de la misma manera que la mayoría de los navegadores. Como resultado, esta función puede ser omitida y conlleva a una vulnerabilidad de Redirección Abierta en la funcionalidad logout. Este bug ha sido corregido en versión 2.4.9 al reemplazar cualquier barra invertida de la URL a redirigir por barras inclinadas para solucionar un cambio particular de ruptura entre las diferentes especificaciones (RFC2396 / RFC3986 y WHATWG). Como solución, esta vulnerabilidad puede ser mitigada configurando "mod_auth_openidc" para que sólo permita la redirección cuyo destino coincida con una expresión regular determinada

A flaw was found in mod_auth_openidc where it does not sanitize redirection URLs properly. This issue could be used by an attacker to facilitate phishing attacks by tricking users into visiting a trusted web application URL that redirects to an external and potentially malicious server. The highest threat from this liability is to confidentiality and integrity.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

None

Integrity

Low

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-05-12 CVE Reserved
2021-07-22 CVE Published
2024-02-26 EPSS Updated
2024-08-03 CVE Updated
2024-08-03 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

CAPEC

References (11)

URL	Tag	Source
https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9	Release Notes
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html	Mailing List
https://security.netapp.com/advisory/ntap-20210902-0001	Third Party Advisory

URL	Date	SRC
https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please	2024-08-03

URL	Date	SRC
https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544	2023-11-07
https://www.oracle.com/security-alerts/cpuapr2022.html	2023-11-07

URL	Date	SRC
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FZVF6BSJLRQZ7PFFR4X5JSU6KUJYNOCU	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QXAWKPT5LXZSUTFSJ6IWSZC7RMYYQXQD	2023-11-07
https://access.redhat.com/security/cve/CVE-2021-32786	2022-05-10
https://bugzilla.redhat.com/show_bug.cgi?id=1986102	2022-05-10

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Openidc Search vendor "Openidc"	Mod Auth Openidc Search vendor "Openidc" for product "Mod Auth Openidc"	< 2.4.9 Search vendor "Openidc" for product "Mod Auth Openidc" and version " < 2.4.9"	-	Affected	in	Apache Search vendor "Apache"	Http Server Search vendor "Apache" for product "Http Server"	>= 2.0.0 <= 2.4.48 Search vendor "Apache" for product "Http Server" and version " >= 2.0.0 <= 2.4.48"	-	Safe
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				33 Search vendor "Fedoraproject" for product "Fedora" and version "33"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				34 Search vendor "Fedoraproject" for product "Fedora" and version "34"		-		Affected