Open Redirect Affecting libapache2-mod-auth-openidc package, versions <2.4.9.4-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
1.74% (77th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LIBAPACHE2MODAUTHOPENIDC-19222809
  • published23 Aug 2026
  • disclosed3 Sept 2021

Introduced: 3 Sep 2021

CVE-2021-39191  (opens in a new tab)
CWE-601  (opens in a new tab)

How to fix?

Upgrade Echo:latest libapache2-mod-auth-openidc to version 2.4.9.4-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libapache2-mod-auth-openidc package and not the libapache2-mod-auth-openidc package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1