10 Noteworthy C and C++ Bugs Found in Open-Source Projects in 2025

2026-01-02 · Source: HackerNoon · Field: Technology & Digital — Software Development & Engineering, Static Analysis · Depth: Advanced, long

Summary

This article details 10 critical bugs discovered in various C and C++ open-source projects throughout 2025, identified using the PVS-Studio static analyzer. The bugs range from implicit type casting issues in Valve's Source SDK (V674) and redundant conditional checks in Erlang (V517), to logical errors in CMake's `CheckImplicitDirItem` function (V523). Other significant findings include dereferencing `std::map::end()` in Windows Terminal (V783), dangling references in OpenCV due to smart pointer misuse (V758), and bitwise operation errors in PHP (V629, V784). The analysis also covers self-assignment issues in Nau Engine's move assignment operator (V794), undefined behavior from calling virtual functions in base class constructors in Wesnoth (V1099), null pointer dereferences in 86Box's `fseek` implementation (V575), and identical sub-expressions in LLVM's `PPCISelLowering.cpp` (V501). Each case highlights common pitfalls in C/C++ development.

Key takeaway

For C/C++ developers working on complex projects, integrating static analysis tools like PVS-Studio into your workflow is crucial. It can proactively identify subtle yet critical bugs, such as implicit type casting, dangling references, and undefined behavior, that often escape manual review and lead to unpredictable runtime issues. Prioritize addressing warnings related to type safety, memory management, and logical redundancies to enhance code robustness and prevent costly debugging cycles.

Key insights

Static analysis effectively uncovers subtle, dangerous bugs across diverse C/C++ open-source projects.

Principles

• Implicit type casting can lead to data loss.
• Redundant conditional checks often hide logical errors.
• Smart pointers do not prevent all dangling reference issues.

Method

The PVS-Studio static analyzer was used to systematically identify and report a variety of programming errors, including type mismatches, logical flaws, and undefined behavior, across C and C++ codebases.

In practice

• Review implicit type conversions, especially with `unsigned char`.
• Implement self-assignment checks in move operators.
• Ensure smart pointers manage object lifetime correctly.

Topics

• PVS-Studio
• C++ Programming Errors
• Undefined Behavior
• Static Code Analysis
• Memory Safety

Code references

• ValveSoftware/source-sdk-2013
• erlang/otp
• microsoft/terminal
• opencv/opencv
• php/php-src

Best for: Software Engineer, Research Scientist

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Editorial summary, takeaway, and curation by AIssential. Original article published by HackerNoon.