CVE-2026-6534: Wireshark USB HID DoS Vulnerability

CVE-2026-6534 Overview

CVE-2026-6534 is an Infinite Loop vulnerability (CWE-835) affecting the USB HID protocol dissector in Wireshark network protocol analyzer. This vulnerability allows an attacker to cause a denial of service condition by providing specially crafted packet capture data that triggers an infinite loop in the dissector component, causing Wireshark to become unresponsive and consume excessive system resources.

Critical Impact

Network analysts and security teams using affected Wireshark versions may experience application crashes or system resource exhaustion when analyzing malicious or malformed USB HID traffic captures, potentially disrupting security monitoring and forensic analysis workflows.

Affected Products

• Wireshark 4.6.0 to 4.6.4
• Wireshark 4.4.0 to 4.4.14

Discovery Timeline

• April 30, 2026 - CVE-2026-6534 published to NVD
• April 30, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6534

Vulnerability Analysis

The vulnerability resides in the USB HID (Human Interface Device) protocol dissector within Wireshark. Protocol dissectors are responsible for parsing and interpreting network packet data for display and analysis. When processing USB HID protocol data, the affected dissector enters an infinite loop condition when encountering malformed or specially crafted input. This results in the application becoming unresponsive and consuming CPU resources indefinitely until forcibly terminated.

The attack requires local access and user interaction, meaning an attacker would need to either convince a user to open a malicious capture file or inject malicious packets into a live capture session being analyzed by Wireshark.

Root Cause

The root cause is classified as CWE-835 (Loop with Unreachable Exit Condition), indicating that the USB HID dissector contains loop logic that, under certain conditions with malformed input, fails to properly terminate. The dissector lacks adequate bounds checking or loop termination conditions when parsing specific USB HID protocol structures, allowing crafted input to create a condition where the exit criteria is never satisfied.

Attack Vector

The attack vector is local, requiring the attacker to deliver a malicious PCAP (packet capture) file to the victim or have the ability to inject packets into traffic being captured by Wireshark. Exploitation scenarios include:

• Sending a malicious capture file via email or file sharing
• Hosting a malicious capture file on a website for download
• Injecting crafted USB HID packets into a network segment being monitored
• Compromising a packet capture repository with poisoned files

The vulnerability impacts availability only, with no direct impact on confidentiality or integrity. However, causing Wireshark to crash or hang during critical security analysis could have secondary security implications.

Detection Methods for CVE-2026-6534

Indicators of Compromise

• Wireshark processes consuming abnormally high CPU utilization (near 100%)
• Wireshark application becoming unresponsive when opening specific capture files
• System resource exhaustion events correlated with Wireshark usage
• Capture files containing unusual or malformed USB HID protocol data

Detection Strategies

• Monitor for Wireshark processes exhibiting CPU spikes or hanging states
• Implement file integrity monitoring on packet capture repositories
• Scan incoming PCAP files for anomalies before analysis
• Use sandboxed environments for analyzing untrusted capture files

Monitoring Recommendations

• Configure process monitoring to alert on Wireshark instances exceeding CPU thresholds
• Implement timeouts for Wireshark analysis operations in automated workflows
• Log and review sources of packet capture files being analyzed
• Monitor for repeated Wireshark crashes or forced terminations

How to Mitigate CVE-2026-6534

Immediate Actions Required

• Upgrade Wireshark to version 4.6.5 or later for the 4.6.x branch
• Upgrade Wireshark to version 4.4.15 or later for the 4.4.x branch
• Avoid opening capture files from untrusted sources until patched
• Consider using isolated analysis environments for processing suspicious captures

Patch Information

Wireshark has released security updates to address this vulnerability. Users should upgrade to the latest available version in their respective release branch. Detailed information about the fix is available in the Wireshark Security Advisory and the GitLab Wireshark Issue tracker.

Workarounds

• Disable the USB HID dissector if not required for analysis workflows
• Process untrusted capture files in isolated virtual machines or containers
• Implement resource limits (cgroups, ulimits) on Wireshark processes to prevent system-wide impact
• Use alternative tools for preliminary analysis of untrusted capture files

# Configuration example - Disable USB HID dissector via command line
wireshark -o "uat:disabled_protos:\"usbhid\""

# Or via tshark for command-line analysis
tshark -o "uat:disabled_protos:\"usbhid\"" -r capture.pcap