HIGH CVSS 7.0
Published: 2026-06-28

CVE-2026-58050

libssh2 libssh2 Security Advisory (CVE-2026-58050)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-58050 impacting libssh2 libssh2. Evaluated with CVSS Base Score of 7.0 (HIGH).

Original NVD Description

Source: NIST NVD
libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.

📊 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
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
Low (I:L)
Partial data modification possible
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product libssh2 / libssh2
Affected Versions *
Weakness Enumeration CWE-190

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-2026-58050 impacting libssh2 libssh2.

⚡ Nuclei Detection Template (YAML) cve-2026-58050.yaml
id: cve-2026-58050

info:
  name: libssh2 libssh2 - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-58050 affecting libssh2 libssh2.
    Evaluation: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-58050
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
    cvss-score: 7.0
    cve-id: CVE-2026-58050
    cwe-id: CWE-190
  tags: cve,cve-2026-58050,libssh2,libssh2,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "libssh2"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-58050.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-58050
# Target: libssh2 libssh2 | CVSS: 7.0 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-58050 (libssh2 libssh2)...")
    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 libssh2 libssh2 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-2026-58050.sh
# Recommended Remediation & Patching Commands for CVE-2026-58050
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install libssh2 2>/dev/null || \
sudo dnf upgrade libssh2 2>/dev/null || \
sudo yum update libssh2

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i libssh2 2>/dev/null || rpm -qa | grep -i libssh2

# 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-2026-58050 in libssh2 libssh2?

Review vendor-specific security notices and update libssh2 libssh2 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-2026-58050?

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-2026-58050?

CVE-2026-58050 is classified with a CVSS 3.1 Base Score of 7.0 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.0
HIGH SEVERITY
CVE ID CVE-2026-58050
Weakness CWE-190
Vendor libssh2
Product libssh2
Published 2026-06-28
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H