Overview
A significant vulnerability, identified as CVE-2025-59375, has been discovered in the libexpat library used in Expat before version 2.7.2. This vulnerability allows attackers to trigger large dynamic memory allocations via small documents submitted for parsing, potentially leading to system compromise or data leakage. Security teams and system administrators of affected systems must prioritize this issue due to its high severity rating and potential impact.
Vulnerability Summary
CVE ID: CVE-2025-59375
Severity: High (CVSS 7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise and data leakage. A successful exploit can lead to unauthorized access, control over affected systems, and potential data leakage.
Affected Products
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Product | Affected Versions
libexpat | Before 2.7.2
How the Exploit Works
The vulnerability lies in the memory allocation system of the libexpat library. Attackers can exploit this by sending a specially crafted document for parsing, which triggers large dynamic memory allocations. This could create a denial of service condition due to memory exhaustion, or potentially allow the execution of arbitrary code if combined with other vulnerabilities.
Conceptual Example Code
The following is a hypothetical example of how an attacker might send a malicious payload to exploit the vulnerability.
POST /parseDocument HTTP/1.1
Host: target.example.com
Content-Type: application/xml
<root>
<!-- Repeat the following line many times to trigger large memory allocation -->
<element attribute="malicious_payload_repeated_to_trigger_memory_allocation"/>
</root>Mitigation Guidance
The primary mitigation for this vulnerability is to apply the vendor’s patch, upgrading libexpat to version 2.7.2 or later. Temporary mitigation can be achieved by implementing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to block or alert on suspicious activities. However, these should not replace patching, which is the most effective way to remediate the vulnerability.