Open Redirect in Openidc Mod Auth
CVE-2021-39191
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.
Vulnerability class: Open Redirect
EPSS: 0.018 (75.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N.
Affected products
- Openidc Mod_auth_openidc
- Zmartzone Mod_auth_openidc — versions <=2.4.9.3
- Debian Debian_linux — versions 10.0
- Fedoraproject Fedora — versions 35, 36
Weakness classification (CWE)
References
- security-advisories@github.com (Vendor Advisory)
- security-advisories@github.com (Exploit)
- security-advisories@github.com (Patch, Third Party Advisory)
- security-advisories@github.com (Release Notes)
- security-advisories@github.com (vendor-advisory)
- security-advisories@github.com (vendor-advisory)
- security-advisories@github.com (mailing-list, Mailing List)
Frequently asked questions
- What is CVE-2021-39191?
- CVE-2021-39191 is a medium-severity vulnerability in Openidc Mod Auth, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 4.7/10. Published 2021-09-03.
- How severe is CVE-2021-39191?
- Medium severity. CVSS v3 base score is 4.7 out of 10.