Skip to content
Fencer Vulns
high 8.0

CVE-2022-39369 json

Service Hostname Discovery Exploitation in phpCAS

published 2022-11-01 4 y ago modified 2026-06-17 4 mo ago also GHSA-8q72-6qq8-xv64 , EUVD-2022-7285

cvss
8.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist apereo/phpcas 1.6.0
  • apereo phpcas 1.6.0
  • php-cas Debian 14, Debian 13, Debian 12 1.6.0-1

debian advisories DEBIAN-CVE-2022-39369

  • php-cas Ubuntu 20.04 LTS 1.3.8-1ubuntu0.20.04.1
  • php-cas Ubuntu 22.04 LTS 1.3.8-1ubuntu0.22.04.1
  • ocsinventory-server Ubuntu 22.04 LTS 2.8.1+dfsg1-1ubuntu0.1
  • php-cas Ubuntu Pro 16.04 LTS 1.3.3-2ubuntu1+esm1

ubuntu advisories UBUNTU-CVE-2022-39369

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
18 mo ago

Exploit prediction

2.43% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 8.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
GitHub 3.1 8.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
packagist apereo/phpcas
<1.6.0
1.6.0

Affected products

  • apereo phpCAS

Classification

Weakness
  • CWE-99 Improper Control of Resource Identifiers
  • CWE-1287 Improper Validation of Specified Type of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.