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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.017 (76.8th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-39191: held from 0.018 to 0.017.

EPSS over last 30 days · oldest: 0.018 · newest: 0.017 · change: -0.000

Affected products

Weakness classification (CWE)

References

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.