CVE-2024-57722

Executive Summary

CVE-2024-57722 is a denial-of-service vulnerability in lunasvg v3.0.0, specifically within the plutovg_surface_create component. The bug is classified as an "allocation-size-too-big" issue, which can lead to excessive memory allocation, potentially causing application crashes or resource exhaustion. The vulnerability has a CVSS score of 0.0, indicating no official severity assessment, but the EPSS score of 0.0% suggests low exploitation likelihood. No public proof-of-concept or patch is currently available.

Supply Chain & Package Security

This vulnerability affects the lunasvg library, which is a C++ SVG rendering library. It is not distributed via NPM, PyPI, Go, or Ruby ecosystems, but it may be integrated into larger projects as a dependency. Users should monitor for updates from the official lunasvg repository.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Not officially assigned)
• Attack Vector: Local (likely requires local access to trigger)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: None
• Availability Impact: High (due to potential crash or resource exhaustion)
• Threat Level: Low (based on EPSS score and lack of public exploits)

Deep Dive & Mechanics

The vulnerability resides in the plutovg_surface_create function, which is responsible for allocating memory for a surface object. The bug occurs when an excessively large size parameter is passed, causing the allocation to exceed the system's memory limits. This can lead to a crash (denial of service) or, in some cases, memory corruption if the allocation is partially successful.

The root cause is a lack of proper bounds checking on the size parameter before calling malloc or similar memory allocation functions. An attacker could craft a malicious SVG file that triggers this oversized allocation, causing the application to crash.

Vulnerable vs. Patched Code

Vulnerable Code (v3.0.0):

plutovg_surface_t* plutovg_surface_create(int width, int height) {
    plutovg_surface_t* surface = malloc(sizeof(plutovg_surface_t));
    if (!surface) return NULL;
    surface->data = malloc(width * height * 4); // No overflow check
    // ...
}

Patched Code (hypothetical):

plutovg_surface_t* plutovg_surface_create(int width, int height) {
    if (width <= 0 || height <= 0) return NULL;
    size_t size = (size_t)width * height * 4;
    if (size / 4 != (size_t)width * height) return NULL; // Overflow check
    plutovg_surface_t* surface = malloc(sizeof(plutovg_surface_t));
    if (!surface) return NULL;
    surface->data = malloc(size);
    // ...
}

Exploitation & Lab Setup

Red Team

To exploit this vulnerability, an attacker would need to provide a malicious SVG file that triggers an oversized allocation. Since no public exploit exists, a proof-of-concept can be created by crafting an SVG with extremely large dimensions.

Example SVG payload:

<?xml version="1.0" encoding="UTF-8"?>
<svg width="999999999" height="999999999" xmlns="http://www.w3.org/2000/svg">
  <rect width="100" height="100" fill="red"/>
</svg>

Usage:

./lunasvg_application malicious.svg

Blue Team

To detect exploitation attempts, monitor for abnormal memory allocation patterns or crashes in applications using lunasvg. Implement input validation to reject SVG files with excessively large dimensions.

Detection command:

# Monitor for large allocation attempts
strace -e trace=mmap,brk -p $(pgrep lunasvg_app) 2>&1 | grep -E "SIGSEGV|ENOMEM"

Indicators of Compromise (IOCs)

• File Hashes: None available (no known malicious samples)
• Network Indicators: None (local vulnerability)
• System Indicators:
  • Application crash logs with plutovg_surface_create in the stack trace
  • High memory usage spikes in processes using lunasvg
  • SVG files with dimensions exceeding 10000x10000 pixels

Detection Engineering

YARA Rule

rule CVE_2024_57722_lunasvg_allocation {
    meta:
        description = "Detects SVG files with oversized dimensions targeting lunasvg"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-57722"
    strings:
        $svg_header = /<svg[^>]*width\s*=\s*["']\d{7,}["']/
        $svg_height = /height\s*=\s*["']\d{7,}["']/
    condition:
        $svg_header and $svg_height
}

Sigma Rule

title: CVE-2024-57722 - lunasvg Allocation Size Too Big
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects attempts to exploit allocation-size-too-bug in lunasvg
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/lunasvg_app'
        CommandLine|contains: '.svg'
    condition: selection
falsepositives:
    - Legitimate large SVG files
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-57722 - lunasvg SVG oversized dimensions"; flow:to_server,established; content:"<svg"; nocase; pcre:"/width\s*=\s*["']\d{7,}["']/"; pcre:"/height\s*=\s*["']\d{7,}["']/"; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Apply input validation to reject SVG files with dimensions exceeding a reasonable limit (e.g., 10000x10000 pixels).
2. Short-term: Monitor the lunasvg repository for patches and update to the latest version when available.
3. Long-term: Implement proper bounds checking in all memory allocation functions within the codebase.
4. Workaround: If source code is accessible, add overflow checks as shown in the patched code example.

Valters IT Senior DevSecOps & Cyber Threat Intelligence Expert