MEDIUM CVSS 5.5
Published: 2025-05-15

CVE-2025-43853

bytecodealliance webassembly_micro_runtime Security Advisory (CVE-2025-43853)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2025-43853 impacting bytecodealliance webassembly_micro_runtime. Evaluated with CVSS Base Score of 5.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
The WebAssembly Micro Runtime's (WAMR) iwasm package is the executable binary built with WAMR VMcore which supports WebAssembly System Interface (WASI) and command line interface. Anyone running WAMR up to and including version 2.2.0 or WAMR built with libc-uvwasi on Windows is affected by a symlink following vulnerability. On WAMR running in Windows, creating a symlink pointing outside of the preopened directory and subsequently opening it with create flag will create a file on host outside of the sandbox. If the symlink points to an existing host file, it's also possible to open it and read its content. Version 2.3.0 fixes the issue.

📊 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
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
None (I:N)
No system modification impact
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product bytecodealliance / webassembly_micro_runtime
Affected Versions *
Weakness Enumeration CWE-61

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-2025-43853 impacting bytecodealliance webassembly_micro_runtime.

⚡ Nuclei Detection Template (YAML) cve-2025-43853.yaml
id: cve-2025-43853

info:
  name: bytecodealliance webassembly_micro_runtime - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2025-43853 affecting bytecodealliance webassembly_micro_runtime.
    Evaluation: The WebAssembly Micro Runtime's (WAMR) iwasm package is the executable binary built with WAMR VMcore which supports WebAssembly System Interface ...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2025-43853
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
    cvss-score: 5.5
    cve-id: CVE-2025-43853
    cwe-id: CWE-61
  tags: cve,cve-2025-43853,bytecodealliance,webassembly_micro_runtime,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "webassembly_micro_runtime"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2025-43853.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2025-43853
# Target: bytecodealliance webassembly_micro_runtime | CVSS: 5.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2025-43853 (bytecodealliance webassembly_micro_runtime)...")
    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 bytecodealliance webassembly_micro_runtime 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-2025-43853.sh
# Recommended Remediation & Patching Commands for CVE-2025-43853
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install webassembly_micro_runtime 2>/dev/null || \
sudo dnf upgrade webassembly_micro_runtime 2>/dev/null || \
sudo yum update webassembly_micro_runtime

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

# 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

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2025-43853 in bytecodealliance webassembly_micro_runtime?

Review vendor-specific security notices and update bytecodealliance webassembly_micro_runtime 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-2025-43853?

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-2025-43853?

CVE-2025-43853 is classified with a CVSS 3.1 Base Score of 5.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.5
MEDIUM SEVERITY
CVE ID CVE-2025-43853
Weakness CWE-61
Vendor bytecodealliance
Product webassembly_micro_runtime
Published 2025-05-15
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N