CVE-2026-18663: Red Hat Directory Server 11

Medium severity, CVSS 5.9. EPSS: 0.5% chance of exploitation in the next 30 days.

A flaw was found in 389-ds-base. The get_ldapmessage_controls_ext() function frees the parsed controls array on the Session Tracking critical-control rejection path without clearing the SLAPI_REQCONTROLS pblock slot. Operation teardown then frees the same pointer again, causing a double-free. An unauthenticated remote attacker can trigger this with a single BIND request carrying a critical Session Tracking control, resulting in heap corruption and potential denial of service.

Affected products

• Red Hat Red Hat Directory Server 11
• Red Hat Red Hat Directory Server 12
• Red Hat Red Hat Directory Server 13
• Red Hat Red Hat Enterprise Linux 10
• Red Hat Red Hat Enterprise Linux 6
• Red Hat Red Hat Enterprise Linux 7
• Red Hat Red Hat Enterprise Linux 8
• Red Hat Red Hat Enterprise Linux 9

Published 2026-08-12. Last modified 2026-08-14.