CVE-2021-32786

Public Exploit
Open Redirect in oidc_validate_redirect_url()

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.

Category

4.7
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.14%
Vendor Advisory fedoraproject.org Vendor Advisory fedoraproject.org
Affected: zmartzone mod_auth_openidc
Published at:
Updated at:

References

Link Tags
https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9 third party advisory release notes
https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-xm4c-5wm5-jqv7 third party advisory
https://github.com/zmartzone/mod_auth_openidc/commit/3a115484eb927bc6daa5737dd84f88ff4bbc5544 third party advisory patch
https://daniel.haxx.se/blog/2017/01/30/one-url-standard-please/ third party advisory exploit
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FZVF6BSJLRQZ7PFFR4X5JSU6KUJYNOCU/ vendor advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QXAWKPT5LXZSUTFSJ6IWSZC7RMYYQXQD/ vendor advisory
https://www.oracle.com/security-alerts/cpuapr2022.html third party advisory patch
https://security.netapp.com/advisory/ntap-20210902-0001/ third party advisory
https://lists.debian.org/debian-lts-announce/2023/04/msg00034.html mailing list

Frequently Asked Questions

What is the severity of CVE-2021-32786?
CVE-2021-32786 has been scored as a medium severity vulnerability.
How to fix CVE-2021-32786?
To fix CVE-2021-32786, 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-2021-32786 being actively exploited in the wild?
It is possible that CVE-2021-32786 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-2021-32786?
CVE-2021-32786 affects zmartzone mod_auth_openidc.
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