---
id: CVE-2026-86345
title: A flaw was found in 389-ds-base
summary: >-
  A flaw was found in 389-ds-base. The server does not discard plaintext bytes
  already buffered from a client connection when negotiating StartTLS, allowing
  an on-path attacker to inject a crafted LDAP message that is processed after
  the T…
severity: critical
cvss: 9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-923
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: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T00:17:04.180'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86345'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-86345'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2529332'
    label: secalert@redhat.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-02T00:04:54.724Z'
---

## Overview

A flaw was found in 389-ds-base. The server does not discard plaintext bytes already buffered from a client connection when negotiating StartTLS, allowing an on-path attacker to inject a crafted LDAP message that is processed after the TLS upgrade and whose response is delivered to the client in place of the client's own pending operation's response, due to messageID collision. This can cause a client application to treat a failed authentication (bind) attempt as successful.

## Remediation

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