MEDIUM CVSS 5.0
Published: 2026-06-18

CVE-2026-11791

redhat directory_server Security Advisory (CVE-2026-11791)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-11791 impacting redhat directory_server. Evaluated with CVSS Base Score of 5.0 (MEDIUM).

Original NVD Description

Source: NIST NVD
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).

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
High (PR:H)
Administrative credentials required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
Low (I:L)
Partial data modification possible
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product redhat / directory_server
Affected Versions 11.0
Weakness Enumeration CWE-416

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-11791 impacting redhat directory_server.

⚡ Nuclei Detection Template (YAML) cve-2026-11791.yaml
id: cve-2026-11791

info:
  name: redhat directory_server - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-11791 affecting redhat directory_server.
    Evaluation: A flaw was found in 389 Directory Server. During schema reload, the attr_syntax_swap_ht() function unconditionally frees attribute syntax information ...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-11791
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H
    cvss-score: 5.0
    cve-id: CVE-2026-11791
    cwe-id: CWE-416
  tags: cve,cve-2026-11791,redhat,directory_server,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "directory_server"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-11791.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-11791
# Target: redhat directory_server | CVSS: 5.0 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-11791 (redhat directory_server)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against redhat directory_server scope (11.0).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-11791.sh
# Recommended Remediation & Patching Commands for CVE-2026-11791
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install directory_server 2>/dev/null || \
sudo dnf upgrade directory_server 2>/dev/null || \
sudo yum update directory_server

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i directory_server 2>/dev/null || rpm -qa | grep -i directory_server

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

Authorities
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Technical Analysis
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❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-11791 in redhat directory_server?

Review vendor-specific security notices and update redhat directory_server packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-11791?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-11791?

CVE-2026-11791 is classified with a CVSS 3.1 Base Score of 5.0 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.0
MEDIUM SEVERITY
CVE ID CVE-2026-11791
Weakness CWE-416
Vendor redhat
Product directory_server
Published 2026-06-18
Vector CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H