libxslt Under Siege: Unpacking the CVE-2025-7425 Use-After-Free Vulnerability

Introduction

XML transformations are foundational to countless applications, from web services to enterprise middleware. At the heart of this ecosystem lies libxslt, a critical library maintained by the GNOME project. Recently, a severe use-after-free vulnerability, CVE-2025-7425, was discovered, threatening the integrity of systems relying on XML transformations. With a CVSS score of 7.8, this flaw demands immediate attention.

Technical Information

Root Cause

The vulnerability originates from improper handling of attribute type (atype) flags within libxslt during XSLT transformations. Specifically, when XSLT functions such as key() generate tree fragments, libxslt modifies these flags without restoring their original state. This oversight corrupts internal memory management structures, particularly affecting the cleanup of ID attributes.

Exploitation Details

Attackers can exploit this flaw by crafting malicious XSLT stylesheets or XML documents that trigger the corrupted memory management pathways. The resulting use-after-free condition can lead to:

Heap corruption
Application crashes
Potential arbitrary code execution

Attack Vectors

Malicious XSLT Processing: Attackers embed crafted XSLT code to trigger the vulnerability.
XML Document Validation: Malicious XML referencing external XSLT stylesheets can exploit the flaw.
Chained Attacks: Potential combination with other vulnerabilities like XML external entity (XXE) attacks.

Affected Systems and Versions

libxslt versions prior to 1.1.43 (upstream fix)
Red Hat Enterprise Linux: libxslt versions before 1.1.34-13.el9_6
Debian Bookworm: libxslt versions before 1.1.35-1+deb12u1
SUSE Linux Enterprise: All unpatched versions

Patch Information

To address this vulnerability, users should apply the following updates:

Red Hat Enterprise Linux: Upgrade to libxslt-1.1.34-13.el9_6 via Red Hat's official repositories.
Debian: Update to libxslt 1.1.35-1+deb12u1.
SUSE Linux Enterprise: Follow advisory SUSE-SU-2025:1125-1 for patching instructions.

If immediate patching is not possible, temporarily disabling XSLT processing or enforcing strict input validation can mitigate risks.

Vendor Security History

libxslt, maintained by the GNOME project, has experienced several memory corruption vulnerabilities historically. While the GNOME project and major Linux distributions like Red Hat and Debian have consistently provided timely patches, recent resource constraints have slowed upstream maintenance, increasing reliance on vendor-specific backports.

Threat Intelligence

Currently, there is no evidence of active exploitation of CVE-2025-7425. However, similar past vulnerabilities in libxslt have been exploited, highlighting the importance of timely patching and vigilance.

References

Security teams and system administrators are strongly advised to prioritize patching and implement recommended mitigations immediately to safeguard their environments.

Source: This report was created using AI

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