HIGH CVSS 7.5
Published: 2026-03-09

CVE-2026-2261

freebsd freebsd Security Advisory (CVE-2026-2261)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2026-2261?
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-2261 impacting freebsd freebsd. Evaluated with CVSS Base Score of 7.5 (HIGH).

Original NVD Description

Source: NIST NVD
Due to a programming error, blocklistd leaks a socket descriptor for each adverse event report it receives. Once a certain number of leaked sockets is reached, blocklistd becomes unable to run the helper script: a child process is forked, but this child dereferences a null pointer and crashes before it is able to exec the helper. At this point, blocklistd still records adverse events but is unable to block new addresses or unblock addresses whose database entries have expired. Once a second, much higher number of leaked sockets is reached, blocklistd becomes unable to receive new adverse event reports. An attacker may take advantage of this by triggering a large number of adverse events from sacrificial IP addresses to effectively disable blocklistd before launching an attack. Even in the absence of attacks or probes by would-be attackers, adverse events will occur regularly in the course of normal operations, and blocklistd will gradually run out file descriptors and become ineffective. The accumulation of open sockets may have knock-on effects on other parts of the system, resulting in a general slowdown until blocklistd is restarted.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
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
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product freebsd / freebsd
Affected Versions 15.0
Weakness Enumeration CWE-772

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-2026-2261 impacting freebsd freebsd.

⚡ Nuclei Detection Template (YAML) cve-2026-2261.yaml 
id: cve-2026-2261

info:
  name: freebsd freebsd - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-2261 affecting freebsd freebsd.
    Evaluation: Due to a programming error, blocklistd leaks a socket descriptor for each adverse event report it receives.

Once a certain number of leaked sockets i...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-2261
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    cvss-score: 7.5
    cve-id: CVE-2026-2261
    cwe-id: CWE-772
  tags: cve,cve-2026-2261,freebsd,freebsd,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "freebsd"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-2261.py 
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-2261
# Target: freebsd freebsd | CVSS: 7.5 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-2261 (freebsd freebsd)...")
    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 freebsd freebsd scope (15.0).")
        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-2026-2261.sh 
# Recommended Remediation & Patching Commands for CVE-2026-2261
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install freebsd 2>/dev/null || \
sudo dnf upgrade freebsd 2>/dev/null || \
sudo yum update freebsd

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

# 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
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-2261 in freebsd freebsd?

Review vendor-specific security notices and update freebsd freebsd 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-2026-2261?

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-2026-2261?

CVE-2026-2261 is classified with a CVSS 3.1 Base Score of 7.5 (HIGH). Check the metric breakdown above for attack vector requirements.

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Risk Snapshot
7.5
HIGH SEVERITY
CVE ID CVE-2026-2261
Weakness CWE-772
Vendor freebsd
Product freebsd
Published 2026-03-09
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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