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Vulnerability · Published Sep 3, 2021 · Assigned by GitHub_M

CVE-2021-39191URL Redirection to Untrusted Site ('Open Redirect') in mod_auth_openidc

Medium 4.7

In plain English

A medium-severity open redirect in mod_auth_openidc from zmartzone. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.7% (higher than 78% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.7Medium
Exploit odds (30 days)1.7%top 22.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8cjose0.6.1-2.module_el8.6.0+2868+44838709ALSA-2022:1823
AlmaLinux:8cjose-devel0.6.1-2.module_el8.6.0+2868+44838709ALSA-2022:1823
AlmaLinux:8mod_auth_openidc2.3.7-11.module_el8.6.0+2868+44838709ALSA-2022:1823
Debian:12libapache2-mod-auth-openidc2.4.9.4-1DEBIAN-CVE-2021-39191
Debian:13libapache2-mod-auth-openidc2.4.9.4-1DEBIAN-CVE-2021-39191
Debian:14libapache2-mod-auth-openidc2.4.9.4-1DEBIAN-CVE-2021-39191
Rocky Linux:8cjose0:0.6.1-2.module+el8.3.0+129+2feafa46RLSA-2022:1823
Rocky Linux:8mod_auth_openidc0:2.3.7-11.module+el8.6.0+840+73eca44eRLSA-2022:1823

Affected products (as reported)

VendorProductVersions
zmartzone mod_auth_openidc <=2.4.9.3

Weakness: CWE-601 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N

References