Overview
CVE-2025-66382 is a low-severity Denial-of-Service (DoS) vulnerability found in libexpat, specifically affecting versions up to 2.7.3. This vulnerability can be triggered by processing a specially crafted XML file, approximately 2 MiB in size, leading to significantly extended processing times, potentially rendering the system unresponsive.
Technical Details
The vulnerability arises from inefficient processing of certain XML structures within libexpat. A malicious actor can craft an XML file that exploits this inefficiency, causing the library to consume excessive CPU resources and prolong processing time. While the file size is relatively small (around 2 MiB), the crafted structure amplifies the processing burden, leading to the DoS condition. The specific details of the exploited XML structure are not explicitly detailed, but involve complex or deeply nested elements/attributes.
CVSS Analysis
- Severity: LOW
- CVSS Score: 2.9
The CVSS score of 2.9 indicates a low-severity vulnerability. This is likely due to the requirement for a malicious actor to supply the crafted XML file, the relatively limited impact (slow processing rather than complete system crash), and the possibility for other system defenses to mitigate the impact.
Possible Impact
The primary impact of CVE-2025-66382 is a Denial of Service. If an application using libexpat processes a malicious XML file, it could experience a significant slowdown in processing time. This can lead to:
- Reduced availability of the application.
- Increased response times for users.
- Resource exhaustion on the server.
Although rated as low severity, in environments where libexpat is used to process XML data from untrusted sources (e.g., file uploads, API endpoints), the impact could be more significant.
Mitigation or Patch Steps
The recommended mitigation is to upgrade to a version of libexpat greater than 2.7.3. Later versions contain fixes that address the inefficient XML processing. If upgrading is not immediately feasible, consider the following:
- Input Validation: Implement strict input validation on XML files processed by libexpat. This can involve limiting the file size, depth of XML elements, and complexity of attributes.
- Resource Limits: Configure resource limits (CPU, memory) for processes using libexpat to prevent a single process from consuming excessive resources.
- Rate Limiting: Implement rate limiting on API endpoints or file upload services that process XML data to prevent a large number of malicious requests from overwhelming the system.
Check for updated versions of `libexpat` in your system’s package manager. For example, on Debian-based systems, you might use:
sudo apt update && sudo apt upgrade libexpat1
