---
id: CVE-2026-11791
title: >-
  389-ds-base: 389-ds-base: use-after-free in schema reload via
  attr_syntax_swap_ht()
summary: >-
  A flaw was found in 389 Directory Server. During schema reload, the
  attr_syntax_swap_ht() function unconditionally frees attribute syntax
  information nodes, bypassing the refcount-based deferred deletion used
  elsewhere in the attribute s…
severity: medium
cvss: 5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H'
cvssSource: cna
cwe:
  - CWE-416
vendor: Red Hat
product: 'redhat-ds:11/389-ds-base'
affected:
  - 'redhat-ds:11/389-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 (all versions)
  - 389-ds-base (all versions)
  - 389-ds-base (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-18T15:24:12.503916Z'
published: '2026-06-18'
updated: '2026-11-07'
sourceUpdated: '2026-11-07T05:01:53.836Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-11791'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-11791'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2485414'
    label: RHBZ#2485414
tags:
  - cve.org
epss: 0.0035
epssPercentile: 0.28782
ingestedAt: '2026-11-05T22:38:31.343Z'
---

## Overview

A flaw was found in 389 Directory Server. During schema reload, the attr_syntax_swap_ht() function unconditionally frees attribute syntax information nodes, bypassing the refcount-based deferred deletion used elsewhere in the attribute syntax subsystem. If an administrator triggers schema reload while concurrent LDAP query traffic is active, worker threads may access freed memory, resulting in use-after-free or double-free and a denial of service (server crash).

## Affected

- `redhat-ds:11/389-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 (all versions)`
- `389-ds-base (all versions)`
- `389-ds-base (all versions)`

## Remediation

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

### Workarounds

Schedule schema reload operations during maintenance windows with reduced LDAP traffic. Minimize schema reload frequency; in replication topologies schema changes propagate automatically. Monitor for unexpected ns-slapd restarts during or immediately after schema reloads. Restrict write access to cn=schema,cn=config to dedicated administrative accounts via LDAP ACIs.