CVE-2021-39191: URL Redirection to Untrusted Site ('Open Redirect') in mod_auth_openidc
First published: Fri Sep 03 2021(Updated: )
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.
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Openidc Mod Auth Openidc | <2.4.9.4 | |
| Fedoraproject Fedora | =35 | |
| Fedoraproject Fedora | =36 | |
| Debian Debian Linux | =10.0 |
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Reference Links
- https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d
- https://github.com/zmartzone/mod_auth_openidc/issues/672
- https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4
- https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2
- https://lists.debian.org/debian-lts-announce/2023/07/msg00020.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/
Frequently Asked Questions
What is CVE-2021-39191?
CVE-2021-39191 is a vulnerability in mod_auth_openidc, allowing an attacker to bypass authentication and gain unauthorized access.
What is mod_auth_openidc?
mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party.
What is the severity of CVE-2021-39191?
CVE-2021-39191 has a severity rating of 6.1 (medium).
How can an attacker exploit CVE-2021-39191?
An attacker can exploit CVE-2021-39191 to bypass authentication and gain unauthorized access to the system.
How can I fix CVE-2021-39191?
To fix CVE-2021-39191, users should update to mod_auth_openidc version 2.4.9.4 or later.
- collector/nvd-index
- agent/author
- agent/type
- agent/softwarecombine
- agent/weakness
- agent/remedy
- agent/description
- collector/nvd-api
- agent/software-canonical-lookup-request
- collector/mitre-cve
- source/MITRE
- agent/last-modified-date
- agent/title
- agent/references
- agent/severity
- agent/tags
- agent/first-publish-date
- agent/event
- vendor/openidc
- canonical/openidc mod auth openidc
- vendor/fedoraproject
- canonical/fedoraproject fedora
- version/fedoraproject fedora/35
- version/fedoraproject fedora/36
- vendor/debian
- canonical/debian debian linux
- version/debian debian linux/10.0