CVE-2026-86344: Red Hat Directory Server 11

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

A flaw was found in 389-ds-base. An unauthenticated remote attacker can send a complete LDAP operation followed by the first bytes of an incomplete LDAPMessage on the same connection, causing the server to hand that connection to a second worker thread before the first worker's result is flushed. The second worker blocks until nsslapd-ioblocktimeout while holding the connection mutex, preventing delivery of the completed operation's result. Repeating this across a small number of connections proportional to the configured worker-thread pool size exhausts the entire pool under default configuration, denying service to all clients (anonymous and authenticated, plaintext and TLS) for as long as the attacker maintains the connections.

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 2026-10-01. Last modified 2026-10-02.