CVE-2023-28857 LDAP password leak in Apereo CAS - GHSL-2023-009

What is CVE-2023-28857?

CVE-2023-28857 is a medium-severity vulnerability in Apereo CAS, published on 27 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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 “ssl_client_cert”. 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 password as for initially configured LDAP server, which can lead to a password leak. An unauthenticated user can leak the password used to LDAP connection configured on server. This issue has been addressed in version 6.6.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Weakness: CWE-522, CWE-200

Which versions are affected by CVE-2023-28857?

2 open source packages ship an affected version, including org.apereo.cas:cas-server-support-x509-core. It affects 1 product.

Products include Apereo Central Authentication Service.

How do I fix CVE-2023-28857?

Upgrade org.apereo.cas:cas-server-support-x509-core to 6.6.6 or later.

Is CVE-2023-28857 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-28857 exists.

Other vulnerabilities in Apereo CAS

• CVE-2023-4612 MFA bypass in Apereo CAS Critical 9.8
• CVE-2024-4399 CAS <= 1.0.0 - Unauthenticated SSRF Critical 9.1
• CVE-2019-10754 Use of Insufficiently Random Values in Apereo CAS High 8.1
• CVE-2020-27178 Improper Authentication in Apereo CAS High 7.5
• CVE-2015-1169 Auth bypass in n/a High 7.5

Sources

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

Also known as GHSA-p78h-m8pv-g9gm.