Apereo CAS vulnerable to credential leaks for LDAP authentication

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N · score source

EPSS

• CVE-2023-28857: 0.50% estimated exploitation activity in the next 30 days; percentile 43.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Apereo CAS is an open source multilingual single sign-on solution for the web. Apereo CAS can be configured to use authentication based on client X509 certificates. These certificates can be provided via TLS handshake or a special HTTP header, such as “sslclientcert”. When checking the validity of the provided client certificate, X509CredentialsAuthenticationHandler performs check that this certificate is not revoked. To do so, it fetches URLs provided in the “CRL Distribution Points” extension of the certificate, which are taken from the certificate itself and therefore can be controlled by a malicious user. If the CAS server is configured to use an LDAP server for x509 authentication with a password, for example by setting a “cas.authn.x509.ldap.ldap-url” and “cas.authn.x509.ldap.bind-credential” properties, X509CredentialsAuthenticationHandler fetches revocation URLs from the certificate, which can be LDAP urls. When making requests to this LDAP urls, Apereo CAS uses the same…

Published by the source

5 Aug 2024, 21:18 UTC

Last modified by the source

5 Aug 2024, 21:19 UTC

Source last checked

26 Oct 2026, 16:30 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-p78h-m8pv-g9gm

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# Patch Next advisory brief: CVE-2023-28857

Advisory: Apereo CAS vulnerable to credential leaks for LDAP authentication
IDs: CVE-2023-28857, GHSA-p78h-m8pv-g9gm
Record: https://patchnext.com/advisories/cve-2023-28857 (revision 1, source checked 26 Oct 2026, 16:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.apereo.cas:cas-server-support-x509-core 6.6.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apereo.cas:cas-server-support-x509-core: affected >= 6.5.0, < 6.6.6; fixed in 6.6.6

## Suggested inspection (read-only)
- Maven org.apereo.cas:cas-server-support-x509-core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.apereo.cas:cas-server-support-x509-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-p78h-m8pv-g9gm (GitHub-reviewed advisory GHSA-p78h-m8pv-g9gm lists affected ranges: Maven org.apereo.cas:cas-server-support-x509-core >=6.5.0 <6.6.6)

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