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CVE-2025-4056: GLib's Windows Woes: The 2GB Signed Integer Overflow

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GLib's Windows Woes: The 2GB Signed Integer Overflow

Vulnerability ID: CVE-2025-4056
CVSS Score: 7.5
Published: 2025-07-28

A classic integer overflow vulnerability in GLib's Windows-specific process spawning logic allows attackers to cause a heap-based buffer overflow. By supplying an argument string approaching 2GB in length, the signed integer length calculation wraps around, leading to an undersized memory allocation and subsequent heap corruption. While primarily a Denial of Service vector, the underlying memory corruption makes this a dangerous flaw in core infrastructure code.

TL;DR

GLib, the utility library powering GNOME and countless other projects, contained a signed integer overflow in its Windows process spawning helper. If an attacker forces an application to spawn a subprocess with a command line string exceeding ~2GB, the length counter overflows. This results in a tiny heap allocation followed by a massive copy operation, obliterating the heap. Patched in version 2.84.1.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-190 (Integer Overflow)
  • Secondary CWE: CWE-122 (Heap-based Buffer Overflow)
  • Attack Vector: Network / Local (Input Dependent)
  • CVSS v3.1: 7.5 (High)
  • Impact: DoS, Potential RCE
  • Platform: Windows (Exclusive)

Affected Systems

  • Windows Applications using GLib
  • GNOME on Windows
  • Cross-platform tools ported to Windows via MSYS2/MinGW
  • GLib: < 2.84.1 (Fixed in: 2.84.1)

Code Analysis

Commit: f1a498e

gspawn-win32: Fix integer overflow in protect_argv_string

- gint len = 0;
+ gsize len = 0;
- retval = g_malloc (len + 1);
+ retval = g_new (gchar, len + 1);
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Exploit Details

  • Research Analysis: Theoretical exploitability demonstrated via code analysis of gspawn-win32.c

Mitigation Strategies

  • Update GLib to version 2.84.1 or later.
  • Implement input validation to restrict command-line argument length.
  • Use alternative IPC mechanisms (pipes, files) for large data transfer instead of command-line arguments.

Remediation Steps:

  1. Identify all applications in your environment using GLib on Windows.
  2. Check the DLL version of libglib-2.0-0.dll.
  3. Replace the DLLs with versions compiled from GLib 2.84.1 source.
  4. Reboot or restart services to load the new library.

References

Read the full report for CVE-2025-4056 on our website for more details including interactive diagrams and full exploit analysis.

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