MEDIUM CVSS 5.2
Published: 2020-12-01

CVE-2020-15257

linuxfoundation containerd Security Advisory (CVE-2020-15257)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2020-15257 impacting linuxfoundation containerd. Evaluated with CVSS Base Score of 5.2 (MEDIUM).

Original NVD Description

Source: NIST NVD
containerd is an industry-standard container runtime and is available as a daemon for Linux and Windows. In containerd before versions 1.3.9 and 1.4.3, the containerd-shim API is improperly exposed to host network containers. Access controls for the shim’s API socket verified that the connecting process had an effective UID of 0, but did not otherwise restrict access to the abstract Unix domain socket. This would allow malicious containers running in the same network namespace as the shim, with an effective UID of 0 but otherwise reduced privileges, to cause new processes to be run with elevated privileges. This vulnerability has been fixed in containerd 1.3.9 and 1.4.3. Users should update to these versions as soon as they are released. It should be noted that containers started with an old version of containerd-shim should be stopped and restarted, as running containers will continue to be vulnerable even after an upgrade. If you are not providing the ability for untrusted users to start containers in the same network namespace as the shim (typically the "host" network namespace, for example with docker run --net=host or hostNetwork: true in a Kubernetes pod) and run with an effective UID of 0, you are not vulnerable to this issue. If you are running containers with a vulnerable configuration, you can deny access to all abstract sockets with AppArmor by adding a line similar to deny unix addr=@**, to your policy. It is best practice to run containers with a reduced set of privileges, with a non-zero UID, and with isolated namespaces. The containerd maintainers strongly advise against sharing namespaces with the host. Reducing the set of isolation mechanisms used for a container necessarily increases that container's privilege, regardless of what container runtime is used for running that container.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product linuxfoundation / containerd
Affected Versions *
Weakness Enumeration CWE-669

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-2020-15257 impacting linuxfoundation containerd.

⚡ Nuclei Detection Template (YAML) cve-2020-15257.yaml
id: cve-2020-15257

info:
  name: linuxfoundation containerd - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2020-15257 affecting linuxfoundation containerd.
    Evaluation: containerd is an industry-standard container runtime and is available as a daemon for Linux and Windows. In containerd before versions 1.3.9 and 1.4.3...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2020-15257
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
    cvss-score: 5.2
    cve-id: CVE-2020-15257
    cwe-id: CWE-669
  tags: cve,cve-2020-15257,linuxfoundation,containerd,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "containerd"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2020-15257.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2020-15257
# Target: linuxfoundation containerd | CVSS: 5.2 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2020-15257 (linuxfoundation containerd)...")
    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 linuxfoundation containerd 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-2020-15257.sh
# Recommended Remediation & Patching Commands for CVE-2020-15257
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install containerd 2>/dev/null || \
sudo dnf upgrade containerd 2>/dev/null || \
sudo yum update containerd

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

# 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-2020-15257 in linuxfoundation containerd?

Review vendor-specific security notices and update linuxfoundation containerd 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-2020-15257?

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-2020-15257?

CVE-2020-15257 is classified with a CVSS 3.1 Base Score of 5.2 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.2
MEDIUM SEVERITY
CVE ID CVE-2020-15257
Weakness CWE-669
Vendor linuxfoundation
Product containerd
Published 2020-12-01
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N