---
id: CVE-2026-86344
title: A flaw was found in 389-ds-base
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 secon…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
vendor: Red Hat
product: 389-ds-base
affected:
  - 389-ds-base (all versions)
  - 'redhat-ds:11/389-ds-base (all versions)'
  - 389-ds-base (all versions)
  - 'redhat-ds:12/389-ds-base (all versions)'
  - 389-ds-base (all versions)
  - 389-ds-base (all versions)
  - 389-ds-base
  - 389-ds-base
  - '389-ds:1.4/389-ds-base (all versions)'
  - 389-ds-base (all versions)
  - 389-ds-base (all versions)
published: '2026-10-01'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T19:16:42.620'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86344'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-86344'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2529329'
    label: secalert@redhat.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86344.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-86344'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86344'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-02T18:22:37.897462Z'
epss: 0.00347
epssPercentile: 0.28151
ingestedAt: '2026-10-01T23:03:32.781Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Directory Server 11, Red Hat Directory Server 12, Red Hat Directory Server 13, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · no fix planned: Red Hat Directory Server 11, Red Hat Directory Server 12, Red Hat Directory Server 13, Red Hat Enterprise Linux 10, … · updated 2026-10-02 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-86344.json)