389-ds-base: 389-ds-base: unauthenticated worker-thread-pool exhaustion via completed-operation-then-incomplete-pdu connection requeue

Summary

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.

Timeline

1. Oct 1, 2026, 9:29 PM UTCCVE published
2. Oct 2, 2026, 6:22 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 2, 2026, 6:22 PM UTCRecord last updated

Affected versions

• 389-ds-base

  Version range not reported

• redhat-ds:11/389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• redhat-ds:12/389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds:1.4/389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

References 2