GHSA-8q72-6qq8-xv64 · Severity: high · Ecosystem: composer — phpCAS vulnerable to Service Hostname Discovery Exploitation
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.
Conclusion & alert: CVE-2022-39369 is rated Moderate Risk (53.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.06%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.99% | 1.06% | +0.08% |
| 2 | 2026-04-27 | 0.93% | 0.99% | +0.06% |
| 3 | 2026-03-04 | — | 0.93% | — |
Full EPSS history (19 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 8.0 | 3.1 | HIGH |
|
2.1 | 5.9 | [email protected] |
| 8.0 | 3.1 | HIGH |
|
2.1 | 5.9 | [email protected] |
GHSA-8q72-6qq8-xv64 · Severity: high · Ecosystem: composer — phpCAS vulnerable to Service Hostname Discovery Exploitation
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2022-39369 not yet assigned priority: Debian including 1 source packages (php-cas), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2022-39369 |
ubuntu
|
medium | CVE-2022-39369 medium priority: Ubuntu including 3 source packages (moodle, ocsinventory-server, php-cas), 22 status rows across 10 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): released 7, ignored 6, not-affected 6, DNE 3. | https://ubuntu.com/security/CVE-2022-39369 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| apereo | phpcas | < 1.6.0 | cpe:2.3:a:apereo:phpcas:*:*:*:*:*:*:*:* |
| fedoraproject | fedora | 35 | cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* |
| fedoraproject | fedora | 36 | cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:* |
| fedoraproject | fedora | 37 | cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:* |