CVE-2025-7424: Xmlsoft Libxslt DOS Vulnerability

CVE-2025-7424 Overview

A type confusion vulnerability has been identified in the libxslt library, a widely-used XSLT transformation engine. The flaw exists due to the same memory field, psvi (Post-Schema-Validation Infoset), being used for both stylesheet and input data during XML transformations. This dual-purpose memory usage can lead to type confusion when processing XML documents, allowing attackers to crash the application or corrupt memory. In some scenarios, this vulnerability may result in denial of service conditions or unexpected application behavior.

Critical Impact

This vulnerability enables remote attackers to cause denial of service through crafted XML documents, potentially affecting any application using libxslt for XML transformations including web servers, content management systems, and container platforms.

Affected Products

• xmlsoft libxslt
• Red Hat OpenShift Container Platform 4.0
• Red Hat Enterprise Linux 6.0, 7.0, 8.0, 9.0, and 10.0

Discovery Timeline

• July 10, 2025 - CVE-2025-7424 published to NVD
• November 4, 2025 - Last updated in NVD database

Technical Details for CVE-2025-7424

Vulnerability Analysis

This vulnerability is classified as CWE-843 (Access of Resource Using Incompatible Type - Type Confusion). The root cause lies in how the libxslt library manages memory during XSLT transformations.

During XML processing, the psvi field serves as a generic pointer that stores post-schema-validation information. However, the libxslt library incorrectly uses this same field for both stylesheet data structures and input document data structures. When the library processes specially crafted input, it may interpret data stored in the psvi field as the wrong type, leading to type confusion.

The vulnerability can be triggered remotely by an attacker who provides malicious XML input to an application that uses libxslt for transformations. No user interaction or authentication is required to exploit this flaw. The impact is primarily on availability, as successful exploitation leads to application crashes or denial of service.

Root Cause

The vulnerability stems from improper type handling in the libxslt library's XML transformation engine. The psvi memory field was designed to hold schema validation metadata but is repurposed across different contexts within the library. When stylesheet data and input data share this field without proper type discrimination, the library may dereference pointers with incorrect type assumptions, leading to memory access violations.

Attack Vector

An attacker can exploit this vulnerability by sending specially crafted XML documents to any service or application that processes XML using the vulnerable libxslt library. The attack vector is network-based, requiring no privileges or user interaction.

The exploitation flow involves:

1. Attacker identifies a target application using libxslt for XML/XSLT processing
2. Attacker crafts a malicious XML document designed to trigger the type confusion in the psvi field handling
3. The malicious document is submitted to the target through any exposed XML processing endpoint
4. When libxslt processes the document, type confusion occurs, causing a crash or memory corruption

Due to the nature of type confusion vulnerabilities, the specific payload depends on the internal memory layout and how the application uses libxslt. Technical details are available in the Red Hat Bug Report #2379228 and the OpenWall OSS Security disclosure.

Detection Methods for CVE-2025-7424

Indicators of Compromise

• Unexpected application crashes in processes using libxslt for XML transformation
• Core dumps or crash logs indicating memory access violations in libxslt library functions
• Increased memory errors or segmentation faults correlated with XML processing activities
• Anomalous XML documents in request logs with unusual or malformed structures

Detection Strategies

• Monitor system logs for application crashes related to libxslt or XSLT processing components
• Implement application-level logging to capture XML parsing exceptions and transformation failures
• Deploy web application firewalls (WAF) with rules to detect malformed or suspicious XML payloads
• Use SentinelOne's Singularity platform to detect memory corruption attempts and abnormal process behavior

Monitoring Recommendations

• Enable crash reporting for applications using libxslt to identify potential exploitation attempts
• Monitor CPU and memory usage patterns for XML processing services to detect resource exhaustion
• Configure alerting for repeated XML parsing failures from specific sources
• Review access logs for endpoints that accept XML input for unusual patterns or high-volume requests

How to Mitigate CVE-2025-7424

Immediate Actions Required

• Inventory all systems and applications using libxslt and prioritize patching based on exposure
• Apply vendor-provided security patches for libxslt as soon as they become available
• Restrict network access to XML processing endpoints where possible
• Implement input validation to reject malformed or suspicious XML documents before processing

Patch Information

Security updates addressing this vulnerability have been released through multiple distribution channels. System administrators should consult their respective vendor advisories:

• Red Hat CVE-2025-7424 Advisory - Official Red Hat security advisory with patch information
• Debian LTS Security Announcement - Debian Long Term Support patch details

For Red Hat Enterprise Linux and OpenShift Container Platform users, apply the latest security updates using your system's package manager. Ensure you are subscribed to security update channels for timely notification of patches.

Workarounds

• Limit exposure by placing XML processing services behind network segmentation or firewalls
• Implement strict input validation to filter potentially malicious XML documents before they reach libxslt
• Consider using alternative XML transformation libraries if immediate patching is not feasible
• Deploy rate limiting on XML processing endpoints to reduce the impact of potential denial of service attacks

# Check installed libxslt version on Red Hat-based systems
rpm -qa | grep libxslt

# Update libxslt to the latest patched version on RHEL/CentOS
sudo yum update libxslt

# On Debian/Ubuntu systems
dpkg -l | grep libxslt
sudo apt-get update && sudo apt-get upgrade libxslt1.1