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Directory ServerApplication · Redhat

CVE-2026-11791

MEDIUM · 5.0 CVSS v3.1 Published 2026-06-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
56/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A memory management flaw in 389 Directory Server's attr_syntax_swap_ht() function bypasses the refcount-based deferred deletion mechanism during schema reload, unconditionally freeing attribute syntax information nodes. When schema reload occurs during active LDAP query traffic, worker threads can access already-freed memory, causing use-after-free or double-free conditions that lead to server crash.

MitigationAdministrators should avoid triggering schema reload operations during periods of high LDAP query traffic, and apply vendor patches when available to address the improper memory management in attr_syntax_swap_ht().

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Directory ServerApplication
Affected:= 11.0= 12.0= 13.0
389 Directory ServerOperating system
Affected:all versions
Enterprise LinuxOperating system
Affected:= 7.0= 8.0= 9.0= 10.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify 389 Directory Server package version
    Run 'rpm -qa | grep -E "(389-ds-base|redhat-ds)"' to list installed directory server packages, then run 'rpm -q --qf "%{VERSION}-%{RELEASE}" <package_name>' to get the exact version
    Affected if Version matches Red Hat Directory Server 11.0, 12.0, 13.0, or any 389 Directory Server version on RHEL 7.0-10.0
  2. Confirm schema reload capability is in use
    Check /etc/dirsrv/slapd-<instance>/schema/ directory for schema files and review directory server configuration for schema reload settings; examine logs in /var/log/dirsrv/slapd-<instance>/ for schema reload operations
    Affected if Schema reload operations are being performed on the directory server
  3. Detect crash events from memory corruption
    Review directory server error logs in /var/log/dirsrv/slapd-<instance>/ for crash reports, segfaults, or use-after-free messages occurring during or after schema reload operations
    Affected if Server crashes or memory corruption errors appear in logs during periods of active LDAP traffic and schema reloads

You are affected if you run an affected version (389 Directory Server any version, or RHEL 7.0-10.0 with directory server) and have experienced server crashes during concurrent LDAP query traffic and schema reload operations.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Administrators should avoid triggering schema reload operations during periods of high LDAP query traffic, and apply vendor patches when available to address the improper memory management in attr_syntax_swap_ht().

Fix this in Directory Server Scoped from the published advisory
  • Consultation3.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,480
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-11791 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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