CVE-2025-66877: Libming Buffer Overflow Vulnerability

CVE-2025-66877 Overview

A buffer overflow vulnerability exists in the dcputchar function within decompile.c in libming version 0.4.8. This stack-based buffer overflow (CWE-121) can be exploited remotely without authentication, potentially allowing attackers to crash applications that process malicious SWF files or other libming-handled content.

Critical Impact

Network-accessible buffer overflow in libming 0.4.8 could lead to denial of service conditions in applications using this library for Flash/SWF file processing.

Affected Products

• libming 0.4.8
• Applications and tools built using libming 0.4.8 for SWF file processing
• Development environments with libming 0.4.8 as a dependency

Discovery Timeline

• 2025-12-29 - CVE-2025-66877 published to NVD
• 2026-01-15 - Last updated in NVD database

Technical Details for CVE-2025-66877

Vulnerability Analysis

This vulnerability is a stack-based buffer overflow (CWE-121) affecting the dcputchar function in the decompile.c source file of libming. The flaw occurs when the decompiler processes specially crafted input that exceeds the expected buffer boundaries. Since libming is a library used for creating and processing SWF (Shockwave Flash) files, applications that utilize this library to parse untrusted SWF content are potentially vulnerable.

The network attack vector indicates that exploitation can occur when an application processes malicious SWF files received over a network connection, such as through web applications or file upload functionality that leverages libming for Flash file handling.

Root Cause

The root cause of this vulnerability lies in insufficient bounds checking within the dcputchar function in decompile.c. When processing input data during the decompilation of SWF content, the function fails to properly validate the size of data being written to a stack-allocated buffer, allowing an attacker to write beyond the buffer's allocated memory space.

Attack Vector

The vulnerability can be exploited remotely by an unauthenticated attacker who can supply malicious input to an application using the vulnerable libming library. The attack scenario involves:

1. An attacker crafts a malicious SWF file or input data designed to trigger the buffer overflow in dcputchar
2. The victim application processes this malicious input using libming 0.4.8
3. The dcputchar function in decompile.c processes the input without proper boundary validation
4. The resulting buffer overflow causes memory corruption, leading to application crash (denial of service)

The vulnerability is exploited through the decompilation functionality, meaning applications that perform SWF decompilation operations are particularly at risk. For technical details regarding this vulnerability, see the GitHub Issue on libming.

Detection Methods for CVE-2025-66877

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using libming for SWF processing
• Core dumps indicating memory corruption in the dcputchar function or decompile.c module
• Abnormal memory access patterns when processing SWF files

Detection Strategies

• Monitor application logs for crashes related to libming library functions, particularly in decompilation operations
• Implement application-level anomaly detection for unusual SWF file processing behavior
• Deploy runtime application self-protection (RASP) solutions capable of detecting buffer overflow attempts
• Use static analysis tools to identify usage of vulnerable libming 0.4.8 in your codebase

Monitoring Recommendations

• Enable crash reporting and core dump collection for applications using libming
• Implement file integrity monitoring for SWF files before processing
• Monitor system resource usage for signs of denial of service conditions
• Deploy endpoint detection and response (EDR) solutions capable of identifying exploitation attempts

How to Mitigate CVE-2025-66877

Immediate Actions Required

• Audit your environment to identify all applications and systems using libming 0.4.8
• Consider restricting or disabling SWF decompilation functionality until a patch is available
• Implement input validation and file type verification before processing SWF content with libming
• Deploy network-level filtering to block untrusted SWF file uploads where possible

Patch Information

At the time of publication, no official patch has been released by the libming project. Organizations should monitor the GitHub Issue on libming for updates regarding a security fix. Consider upgrading to newer versions of libming when a patched release becomes available.

Workarounds

• Avoid processing untrusted SWF files with applications using libming 0.4.8
• Implement sandboxing or containerization for applications that must process SWF content
• Use alternative libraries for SWF processing if available and compatible with your use case
• Apply defense-in-depth measures including ASLR, DEP/NX, and stack canaries at the system level

# Check for libming version in your environment
find /usr -name "*libming*" -o -name "*ming*" 2>/dev/null
ldconfig -p | grep ming

# Verify libming version if installed via package manager
apt list --installed 2>/dev/null | grep ming
rpm -qa | grep ming