CVE-2026-29976: hcxpcapngtool Buffer Overflow Vulnerability

CVE-2026-29976 Overview

A Buffer Overflow vulnerability has been identified in ZerBea hcxpcapngtool version 7.0.1-43-g2ee308e. This vulnerability exists within the getradiotapfield() function and allows a local attacker to obtain sensitive information or cause a denial of service condition. The hcxtools suite is commonly used for Wi-Fi security auditing and analysis, making this vulnerability particularly relevant for security professionals and penetration testers.

Critical Impact

Local attackers can exploit the buffer overflow in getradiotapfield() to cause application crashes or potentially leak sensitive memory contents during Wi-Fi capture file processing.

Affected Products

• ZerBea hcxpcapngtool v. 7.0.1-43-g2ee308e
• hcxtools suite containing vulnerable hcxpcapngtool versions

Discovery Timeline

• 2026-03-26 - CVE-2026-29976 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-29976

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw resides in the getradiotapfield() function within hcxpcapngtool, a tool used for converting Wi-Fi packet capture files between different formats.

When processing malformed or specially crafted input data, the function fails to properly validate buffer boundaries before copying data. This allows an attacker with local access to provide malicious input that overflows the allocated buffer space, potentially corrupting adjacent memory regions.

The vulnerability requires local access to exploit, meaning an attacker must have the ability to execute hcxpcapngtool with malicious input files on the target system. While remote exploitation is not directly possible, scenarios involving processing of untrusted capture files could expose systems to this vulnerability.

Root Cause

The root cause is improper bounds checking in the getradiotapfield() function. The function processes radiotap header fields from packet capture data without adequately verifying that the input data fits within the allocated buffer. This is a classic instance of CWE-120 where the size of the source data is not checked before being copied to a fixed-size destination buffer.

Attack Vector

The attack requires local access to the target system. An attacker can exploit this vulnerability by:

1. Crafting a malicious packet capture file with specially formatted radiotap header fields
2. Executing hcxpcapngtool against the malicious file
3. Triggering the buffer overflow in getradiotapfield() during file processing

The overflow primarily leads to denial of service through application crashes, though information disclosure may also be possible depending on memory layout and exploitation technique.

For technical details on the vulnerability, refer to the GitHub Issue Report which contains the original vulnerability disclosure.

Detection Methods for CVE-2026-29976

Indicators of Compromise

• Unexpected crashes or segmentation faults when running hcxpcapngtool
• Core dump files generated by hcxpcapngtool during normal operations
• Unusual memory consumption patterns during packet capture file processing
• Error messages indicating buffer-related issues in application logs

Detection Strategies

• Monitor for abnormal hcxpcapngtool process terminations or crash events
• Implement file integrity monitoring for capture files processed by security tools
• Deploy endpoint detection solutions capable of identifying buffer overflow exploitation attempts
• Use memory safety tools like AddressSanitizer during development and testing

Monitoring Recommendations

• Enable crash reporting and logging for hcxtools suite components
• Monitor system logs for repeated application failures involving hcxpcapngtool
• Implement alerting for unusual patterns in packet capture file processing workflows
• Review input files from untrusted sources before processing with vulnerable tools

How to Mitigate CVE-2026-29976

Immediate Actions Required

• Update hcxtools to the latest version that addresses this vulnerability
• Avoid processing packet capture files from untrusted sources with vulnerable versions
• Implement input validation for files processed by hcxpcapngtool
• Consider running hcxpcapngtool in a sandboxed environment when processing untrusted files

Patch Information

Check the hcxtools GitHub repository for the latest release that addresses this vulnerability. Users should update to a patched version as soon as one becomes available from the maintainer.

Workarounds

• Process only trusted packet capture files until a patch is applied
• Run hcxpcapngtool within a container or virtual machine to limit impact
• Implement strict file validation before processing with vulnerable tools
• Use alternative tools for processing untrusted capture files until the vulnerability is addressed

# Recommended: Run hcxpcapngtool in a sandboxed environment
# Example using firejail sandbox
firejail --private --net=none hcxpcapngtool -o output.22000 capture.pcapng

# Alternatively, verify file source before processing
sha256sum capture.pcapng  # Verify file integrity