CVE-2021-39191

Public Exploit
URL Redirection to Untrusted Site ('Open Redirect') in mod_auth_openidc

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 2.4.9.4, 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.

Category

4.7
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.46%
Vendor Advisory fedoraproject.org Vendor Advisory fedoraproject.org Vendor Advisory github.com
Affected: zmartzone mod_auth_openidc
Published at:
Updated at:

References

Link Tags
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2 vendor advisory
https://github.com/zmartzone/mod_auth_openidc/issues/672 exploit
https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d third party advisory patch
https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4 release notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/ vendor advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/ vendor advisory
https://lists.debian.org/debian-lts-announce/2023/07/msg00020.html mailing list

Frequently Asked Questions

What is the severity of CVE-2021-39191?
CVE-2021-39191 has been scored as a medium severity vulnerability.
How to fix CVE-2021-39191?
To fix CVE-2021-39191, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-39191 being actively exploited in the wild?
It is possible that CVE-2021-39191 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-39191?
CVE-2021-39191 affects zmartzone mod_auth_openidc.
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