CVE-2024-57719

Executive Summary

CVE-2024-57719 is a denial-of-service vulnerability in lunasvg v3.0.0, a lightweight SVG rendering library. The vulnerability manifests as a segmentation violation (crash) in the blend_transformed_tiled_argb.isra.0 component, likely triggered by malformed or specially crafted SVG input. With a CVSS score of 0.0 (placeholder) and no known public exploit or patch, this issue currently poses a low immediate risk but could be leveraged in denial-of-service attacks against applications using lunasvg for SVG parsing. The root cause appears to be a null pointer dereference or memory corruption during tiled ARGB blending operations.

Supply Chain & Package Security

lunasvg is a C++ library distributed via GitHub and potentially included as a dependency in other projects. No official package manager (NPM, PyPI, Go, Ruby) distribution is confirmed. Users should verify if their software supply chain includes lunasvg v3.0.0 and monitor for updates.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (placeholder – likely medium to high based on crash impact)
• Attack Vector: Network (if SVG input is accepted from untrusted sources)
• Attack Complexity: Low (malformed SVG can be crafted)
• Privileges Required: None
• User Interaction: None (if SVG is processed automatically)
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High (crash leads to denial of service)
• Threat Level: Medium (denial-of-service only, no data breach)

Deep Dive & Mechanics

The vulnerability resides in the blend_transformed_tiled_argb.isra.0 function within lunasvg’s rendering pipeline. This function handles tiled ARGB (alpha, red, green, blue) blending with transformations. A segmentation violation (SIGSEGV) occurs when the function attempts to access memory through an invalid pointer, likely due to:

• A null pointer dereference when a tiled pattern or transformation matrix is malformed.
• Out-of-bounds memory access during pixel blending loops.
• Improper handling of edge cases in SVG tiling attributes (e.g., patternUnits, patternTransform).

The crash is reproducible by feeding a specially crafted SVG file that triggers the vulnerable code path. No public proof-of-concept exists, but the crash indicates a memory safety issue.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is in lunasvg v3.0.0. The specific function blend_transformed_tiled_argb.isra.0 is likely in the source file source/blend.cpp or similar. A hypothetical patch would add null pointer checks and bounds validation before memory access.

Vulnerable code (hypothetical):

void blend_transformed_tiled_argb(Image& img, const Tile& tile, const Matrix& transform) {
    // No null check on tile or transform
    for (int y = 0; y < img.height; ++y) {
        for (int x = 0; x < img.width; ++x) {
            Point p = transform * Point(x, y);
            // Potential null dereference if tile.data is null
            Color c = tile.data[p.x % tile.width][p.y % tile.height];
            // ...
        }
    }
}

Patched code (hypothetical):

void blend_transformed_tiled_argb(Image& img, const Tile& tile, const Matrix& transform) {
    if (!tile.data || tile.width == 0 || tile.height == 0) return; // Null check
    for (int y = 0; y < img.height; ++y) {
        for (int x = 0; x < img.width; ++x) {
            Point p = transform * Point(x, y);
            int px = p.x % tile.width;
            int py = p.y % tile.height;
            if (px < 0) px += tile.width; // Bounds fix
            if (py < 0) py += tile.height;
            Color c = tile.data[px][py];
            // ...
        }
    }
}

Exploitation & Lab Setup

Red Team

Objective: Cause denial of service by crashing applications using lunasvg v3.0.0.

Lab Setup:

1. Install lunasvg v3.0.0 from source: git clone https://github.com/sammycage/lunasvg.git && cd lunasvg && git checkout v3.0.0 && mkdir build && cd build && cmake .. && make
2. Create a malicious SVG file that triggers the crash. Example (hypothetical):

<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
  <defs>
    <pattern id="p" patternUnits="userSpaceOnUse" width="10" height="10">
      <rect width="10" height="10" fill="red"/>
    </pattern>
  </defs>
  <rect width="100" height="100" fill="url(#p)" transform="scale(0)"/>
</svg>

3. Run the lunasvg parser: ./lunasvg malicious.svg
4. Observe segmentation fault.

Exploit Code: No public exploit available. The above SVG is a theoretical trigger.

Blue Team

Detection:

• Monitor for crashes in applications using lunasvg (e.g., via core dumps or application logs).
• Use file integrity monitoring to detect unexpected SVG files.
• Implement input validation for SVG files before processing (e.g., reject files with malformed pattern elements).

Mitigation:

• Disable SVG processing if not required.
• Use a sandboxed environment for SVG parsing.
• Apply memory safety tools (e.g., AddressSanitizer) during development.

Indicators of Compromise (IOCs)

• File Hashes (malicious SVG): None publicly known.
• Process Behavior: Segmentation fault (SIGSEGV) in blend_transformed_tiled_argb.isra.0.
• Network: No network indicators (local crash).
• Logs: Application crash logs with signal 11 (SIGSEGV).

Detection Engineering

YARA Rule

rule CVE_2024_57719_lunasvg_crash {
    meta:
        description = "Detects SVG files likely to trigger CVE-2024-57719 in lunasvg v3.0.0"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-57719"
    strings:
        $pattern = /<pattern[^>]*patternUnits\s*=\s*["']userSpaceOnUse["'][^>]*>/
        $transform = /transform\s*=\s*["'][^"']*scale\s*\(\s*0\s*\)[^"']*["']/
    condition:
        $pattern and $transform
}

Sigma Rule

title: CVE-2024-57719 lunasvg Crash Detection
id: 8a3b2c1d-4e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects crash events in lunasvg v3.0.0 related to CVE-2024-57719
author: Valters IT
date: 2025-04-10
logsource:
    product: linux
    service: syslog
detection:
    selection:
        - "SIGSEGV"
        - "blend_transformed_tiled_argb"
    condition: selection
falsepositives:
    - Other crashes in lunasvg
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-57719 lunasvg Malicious SVG Transfer"; flow:to_client,established; file.data; content:"<pattern"; content:"patternUnits"; content:"userSpaceOnUse"; content:"transform"; content:"scale(0)"; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable SVG processing in applications using lunasvg v3.0.0 until a patch is available.
• Short-term: Implement input validation to reject SVG files with suspicious pattern or transform attributes.
• Long-term: Monitor the lunasvg repository for patches and update to a fixed version once released.
• Workaround: Use an alternative SVG library (e.g., librsvg, nanosvg) if possible.

Valters IT
DevSecOps & Cyber Threat Intelligence