CVE-2021-39191
4.7 · MEDIUMOverview
CVE-2021-39191 is a medium-severity vulnerability affecting openidc mod_auth_openidc. It was published on September 3, 2021 and has a CVSS 3.1 base score of 4.7 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.7, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from openidc. Update mod_auth_openidc to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| openidc | mod_auth_openidc | >= 0, < 2.4.9.4 | Affected |
References
Frequently Asked Questions
What is CVE-2021-39191?
CVE-2021-39191 is a medium-severity vulnerability affecting openidc mod_auth_openidc. It was published on September 3, 2021 and has a CVSS 3.1 base score of 4.7 (MEDIUM).
How severe is CVE-2021-39191?
This vulnerability has a CVSS 3.1 base score of 4.7, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-39191?
Check the references section for vendor advisories and patches from openidc. Update mod_auth_openidc to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-39191?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-39191 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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