CVE-2022-39369 Service Hostname Discovery Exploitation in phpCAS

What is CVE-2022-39369?

CVE-2022-39369 is a high-severity vulnerability in Fedoraproject Fedora, published on 1 Nov 2022.

Official description

phpCAS is an authentication library that allows PHP applications to easily authenticate users via a Central Authentication Service (CAS) server. The phpCAS library uses HTTP headers to determine the service URL used to validate tickets. This allows an attacker to control the host header and use a valid ticket granted for any authorized service in the same SSO realm (CAS server) to authenticate to the service protected by phpCAS. Depending on the settings of the CAS server service registry in worst case this may be any other service URL (if the allowed URLs are configured to "^(https)://.*") or may be strictly limited to known and authorized services in the same SSO federation if proper URL service validation is applied. This vulnerability may allow an attacker to gain access to a victim's account on a vulnerable CASified service without victim's knowledge, when the victim visits attacker's website while being logged in to the same CAS server. phpCAS 1.6.0 is a major version upgrade that starts enforcing service URL discovery validation, because there is unfortunately no 100% safe default config to use in PHP. Starting this version, it is required to pass in an additional service base URL argument when constructing the client class. For more information, please refer to the upgrading doc. This vulnerability only impacts the CAS client that the phpCAS library protects against. The problematic service URL discovery behavior in phpCAS < 1.6.0 will only be disabled, and thus you are not impacted from it, if the phpCAS configuration has the following setup: 1. `phpCAS::setUrl()` is called (a reminder that you have to pass in the full URL of the current page, rather than your service base URL), and 2. `phpCAS::setCallbackURL()` is called, only when the proxy mode is enabled. 3. If your PHP's HTTP header input `X-Forwarded-Host`, `X-Forwarded-Server`, `Host`, `X-Forwarded-Proto`, `X-Forwarded-Protocol` is sanitized before reaching PHP (by a reverse proxy, for example), you will not be impacted by this vulnerability either. If your CAS server service registry is configured to only allow known and trusted service URLs the severity of the vulnerability is reduced substantially in its severity since an attacker must be in control of another authorized service. Otherwise, you should upgrade the library to get the safe service discovery behavior.

Weakness: CWE-99, CWE-1287

Which versions are affected by CVE-2022-39369?

2 open source packages ship an affected version, including apereo/phpcas. It affects 2 products.

Products include Apereo Phpcas, Fedoraproject Fedora.

How do I fix CVE-2022-39369?

Upgrade apereo/phpcas to 1.6.0 or later.

Is CVE-2022-39369 being exploited?

There is no known exploitation of CVE-2022-39369 in the wild and no public exploit code.

Other vulnerabilities in Fedoraproject Fedora

• CVE-2017-1000071 Auth bypass in n/a High 8.1
• CVE-2010-3692 Path traversal in n/a Medium 6.4
• CVE-2012-5583 Weak cryptography in n/a Medium 5.8
• CVE-2012-1105 Information disclosure in php-pear-CAS Medium 5.5
• CVE-2012-1104 Security feature bypass in phpCAS Medium 5.3

All Fedoraproject Fedora vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2022-39369, DLA-3485-1, GHSA-8q72-6qq8-xv64, MGASA-2022-0432, UBUNTU-CVE-2022-39369, USN-6913-1 and 2 more.