CVE-2024-45492: Libexpat Buffer Overflow Vulnerability

CVE-2024-45492 Overview

An issue was discovered in libexpat before version 2.6.3. The vulnerability occurs in the nextScaffoldPart function within xmlparse.c, leading to an integer overflow for m_groupSize on 32-bit platforms where UINT_MAX equals SIZE_MAX, potentially allowing an attacker to execute arbitrary code.

Critical Impact

This vulnerability has been classified as CRITICAL, impacting libexpat with a CVSS score of 9.8. Due to its network attack vector and the potential compromise of confidentiality, integrity, and availability, immediate remediation is crucial.

Affected Products

• libexpat_project libexpat

Discovery Timeline

• 2024-08-30 - CVE CVE-2024-45492 published to NVD
• 2025-11-04 - Last updated in NVD database

Technical Details for CVE-2024-45492

Vulnerability Analysis

The vulnerability arises from an integer overflow issue in the nextScaffoldPart function of xmlparse.c. This issue can lead to incorrect memory allocation, which attackers could exploit. On affected platforms, improper handling of large integer values causes an overflow, compromising the software's integrity.

Root Cause

The root cause is traced to inadequate validation of input size before performing arithmetic operations on m_groupSize, leading to integer overflow.

Attack Vector

This vulnerability can be exploited via a network attack vector, allowing remote attackers to send specially crafted XML data to trigger the overflow.

// Example exploitation code (sanitized)
#include <stdio.h>
#include <limits.h>

void vulnerableFunction(size_t groupSize) {
    size_t newSize = groupSize + 100; // Potential overflow if groupSize is large
    char *buffer = malloc(newSize);
}

int main() {
    size_t largeSize = UINT_MAX - 50;
    vulnerableFunction(largeSize);
    return 0;
}

Detection Methods for CVE-2024-45492

Indicators of Compromise

• Unexpected application crashes
• Unusual spikes in network traffic directed at libexpat services
• Memory allocation failures logged by the operating system

Detection Strategies

Detection of this vulnerability involves monitoring for anomalous behavior in applications using libexpat, such as memory errors or misallocations. Utilize intrusion detection systems (IDS) configured to alert on patterns indicative of a buffer overflow.

Monitoring Recommendations

Deploy endpoint protection solutions like SentinelOne that continuously monitor processes for anomalous behavior and detect memory manipulation attempts, ensuring rapid response to identified threats.

How to Mitigate CVE-2024-45492

Immediate Actions Required

• Update to libexpat version 2.6.3 or later as soon as possible.
• Implement input validation and boundary checks in your applications utilizing libexpat.
• Restrict network access to systems running vulnerable versions of libexpat.

Patch Information

Refer to the official patch provided by the libexpat_project. Ensure all systems are updated using this patch to mitigate the risk.

Workarounds

If patching immediately is not feasible, consider implementing boundary checks manually within the application code and restrict XML parsing functionality to trusted sources.

# Configuration example
iptables -A INPUT -s 0.0.0.0/0 -p tcp --dport 12345 -j DROP