MEDIUM CVSS 6.5
Published: 2026-04-28

CVE-2026-6238

gnu glibc Security Advisory (CVE-2026-6238)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-6238 impacting gnu glibc. Evaluated with CVSS Base Score of 6.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2.43 fail to validate the RDATA content against the RDATA length in a DNS response when processing A6, CERT, LOC, TKEY or TSIG records, which may allow an attacker to craft a DNS response, causing a target application to crash or read uninitialized memory. These functions are for application debugging only and hence not in the path of code executed by the DNS resolver. Further, they have been deprecated since version 2.34 and should not be used by any new applications. Applications should consider porting away from these interfaces since they may be removed in future versions.

📊 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
Low (C:L)
Partial information leakage
Integrity
None (I:N)
No system modification impact
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product gnu / glibc
Affected Versions *
Weakness Enumeration CWE-126

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-2026-6238 impacting gnu glibc.

⚡ Nuclei Detection Template (YAML) cve-2026-6238.yaml
id: cve-2026-6238

info:
  name: gnu glibc - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-6238 affecting gnu glibc.
    Evaluation: The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2.43 fail to validate the RDATA content a...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-6238
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
    cvss-score: 6.5
    cve-id: CVE-2026-6238
    cwe-id: CWE-126
  tags: cve,cve-2026-6238,gnu,glibc,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "glibc"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-6238.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-6238
# Target: gnu glibc | CVSS: 6.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-6238 (gnu glibc)...")
    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 gnu glibc scope (*).")
        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-2026-6238.sh
# Recommended Remediation & Patching Commands for CVE-2026-6238
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install glibc 2>/dev/null || \
sudo dnf upgrade glibc 2>/dev/null || \
sudo yum update glibc

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

# 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.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-6238 in gnu glibc?

Review vendor-specific security notices and update gnu glibc 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-2026-6238?

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-2026-6238?

CVE-2026-6238 is classified with a CVSS 3.1 Base Score of 6.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
6.5
MEDIUM SEVERITY
CVE ID CVE-2026-6238
Weakness CWE-126
Vendor gnu
Product glibc
Published 2026-04-28
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L