CVE-2023-28857

highpriority · track · 30EPSS 0.005 · 43 %ileEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.50% (43rd) EPSS

CVSS 7.5 · high

Is it mine?

5 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · osv

EPSS · scored 2026-10-28

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4–7.5

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:Nsecondary · ENISA EU

v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:Nsecondary · security-advisories@github.comexploitability 2.2 · impact 1.4

v3.14mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:Nsecondary · OSV

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-522USprimaryCWE-200USCWE-200USCWE-522US

affected products (5)

Products and version ranges known to be affected.

CAS6.5.0, → 6.5.9.1enisa_euvdEU
CAS6.6.0, → 6.6.6enisa_euvdEU
apereo central authentication service6.5.0 → 6.5.9.1nvdUScpe:2.3:a:apereo:central_authentication_service:*:*:*:*:*:*:*:*
apereo central authentication service6.6.0 → 6.6.6nvdUScpe:2.3:a:apereo:central_authentication_service:*:*:*:*:*:*:*:*
Maven org.apereo.cas:cas-server-support-x509-core6.5.0 → 6.6.6osvUSpkg:maven/org.apereo.cas/cas-server-support-x509-core

advisories (1)

Vendor and ecosystem advisories describing this.

GHSA-p78h-m8pv-g9gmApereo CAS vulnerable to credential leaks for LDAP authentication2024-08-05ghsa · osvUS
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.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd osv NVD CVE.org MITRE

published 2023-06-27modified 2026-06-17

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references (10)

External citations — patches, advisories, analysis.

scry

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