CVE-2025-10728: SVG Pattern Element DoS Vulnerability

CVE-2025-10728 Overview

CVE-2025-10728 is a critical Denial of Service vulnerability affecting the Qt SVG rendering module. When the module processes an SVG file containing a <pattern> element, it may enter an uncontrolled recursive rendering loop, ultimately causing a stack overflow and application crash. This vulnerability allows attackers to craft malicious SVG files that can crash any application utilizing the vulnerable Qt SVG library.

Critical Impact

Applications using Qt's SVG rendering capabilities are susceptible to denial of service attacks through specially crafted SVG files containing recursive pattern elements, potentially causing service disruption and system instability.

Affected Products

• Qt SVG Module (qtsvg)
• Applications using Qt SVG rendering functionality

Discovery Timeline

• 2025-10-03 - CVE CVE-2025-10728 published to NVD
• 2025-10-06 - Last updated in NVD database

Technical Details for CVE-2025-10728

Vulnerability Analysis

This vulnerability is classified under CWE-674 (Uncontrolled Recursion), indicating that the Qt SVG rendering module fails to properly handle recursive references within <pattern> elements. When rendering SVG content, the module processes pattern definitions to apply repeated graphical elements. However, when a pattern references itself either directly or through a chain of references, the renderer enters an unbounded recursive state.

The recursive rendering continues until the call stack is exhausted, resulting in a stack overflow condition. This causes the affected application to crash abruptly, denying service to legitimate users. The vulnerability is particularly concerning because SVG files are commonly used in web applications, document viewers, and graphics editing software.

Root Cause

The root cause of this vulnerability lies in the Qt SVG module's failure to implement proper recursion depth checking or cycle detection when rendering <pattern> elements. The rendering logic does not track which patterns have already been visited during the rendering tree traversal, allowing circular references to trigger infinite recursion.

When a <pattern> element references another pattern (or itself) as part of its fill or stroke definitions, the renderer attempts to resolve and render each pattern reference without maintaining a visited set or imposing depth limits. This design flaw enables attackers to construct SVG files with deliberately recursive pattern structures.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to deliver a malicious SVG file to the target system. Attack scenarios include:

• Uploading malicious SVG files to web applications that process user-submitted images
• Sending SVG attachments via email to be opened by vulnerable email clients
• Embedding malicious SVG content in documents or presentations
• Hosting malicious SVG files on websites visited by users with vulnerable browsers or applications

The vulnerability is triggered when the malicious SVG file containing recursive <pattern> elements is parsed and rendered by the Qt SVG module. The attacker does not require any privileges on the target system, and no user interaction beyond opening the file is necessary.

The exploitation mechanism involves creating an SVG file where a <pattern> element contains a reference that creates a circular dependency. When the Qt SVG renderer encounters this pattern and attempts to render it, the recursive nature of the references causes the renderer to call itself repeatedly until the stack is exhausted.

Technical details and the patch implementation can be found in the Qt Project Code Review.

Detection Methods for CVE-2025-10728

Indicators of Compromise

• Application crashes with stack overflow errors when processing SVG files
• Abnormally high CPU utilization during SVG rendering operations
• System logs showing repeated crashes of applications using Qt SVG libraries
• Core dumps or crash reports indicating recursive function calls in SVG rendering code

Detection Strategies

• Monitor application crash logs for stack overflow exceptions related to SVG processing
• Implement file scanning for SVG files containing suspicious recursive <pattern> element structures
• Deploy application monitoring to detect abnormal memory and CPU usage patterns during file processing
• Use static analysis tools to identify SVG files with circular pattern references before processing

Monitoring Recommendations

• Enable verbose logging for SVG file processing operations in Qt-based applications
• Configure system-level crash reporting to capture and analyze stack overflow events
• Implement rate limiting on SVG file uploads to minimize potential denial of service impact
• Monitor application health endpoints for unexpected service disruptions

How to Mitigate CVE-2025-10728

Immediate Actions Required

• Update Qt SVG module to the patched version as soon as it becomes available
• Implement input validation to reject SVG files with suspicious pattern structures
• Consider disabling SVG processing temporarily in critical applications if patches are unavailable
• Deploy sandboxed environments for processing untrusted SVG files to limit crash impact

Patch Information

A patch addressing this vulnerability has been submitted to the Qt project. The fix implements proper recursion depth checking and cycle detection in the SVG pattern rendering code. Organizations should monitor the Qt Project Code Review for the official release containing this fix and apply updates as they become available.

Workarounds

• Sanitize incoming SVG files by pre-processing and removing or flattening <pattern> elements
• Implement wrapper processes with stack size limits to prevent system-wide impact from stack overflows
• Use alternative SVG rendering libraries that include recursion protection until Qt is patched
• Configure application firewalls or content filters to block SVG files from untrusted sources