CVE-2026-6869: Wireshark WebSocket DoS Vulnerability

CVE-2026-6869 Overview

CVE-2026-6869 is a denial of service vulnerability affecting Wireshark's WebSocket protocol dissector. The vulnerability exists in Wireshark versions 4.6.0 through 4.6.4 and versions 4.4.0 through 4.4.14. When processing specially crafted WebSocket traffic, the dissector can crash, leading to application termination and potential disruption of network analysis operations.

Critical Impact

Attackers can cause Wireshark to crash by sending malicious WebSocket packets, disrupting network monitoring and forensic analysis activities.

Affected Products

• Wireshark 4.6.0 to 4.6.4
• Wireshark 4.4.0 to 4.4.14

Discovery Timeline

• 2026-04-30 - CVE CVE-2026-6869 published to NVD
• 2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-6869

Vulnerability Analysis

This vulnerability is classified under CWE-1325 (Improperly Controlled Sequential Memory Allocation), indicating the WebSocket dissector fails to properly manage memory allocation during packet processing. The flaw requires local access, meaning an attacker must be able to provide a malicious capture file or be in a position to inject WebSocket traffic that Wireshark will analyze. While no confidentiality or integrity impacts exist, the availability impact is high, resulting in complete application failure when the vulnerability is triggered.

Root Cause

The root cause lies in improper handling of sequential memory allocation within the WebSocket protocol dissector. When processing WebSocket frames, the dissector fails to properly validate or control memory allocation sequences, leading to an exploitable condition that causes the application to crash. This type of vulnerability typically occurs when parsers do not properly bound memory operations during protocol parsing, especially when handling malformed or adversarial input.

Attack Vector

The attack requires local access with user interaction. An attacker could exploit this vulnerability by:

1. Crafting a malicious packet capture file (PCAP/PCAPNG) containing specially crafted WebSocket frames
2. Convincing a user to open the malicious capture file in Wireshark
3. Alternatively, injecting malicious WebSocket traffic into a network that is being actively monitored by Wireshark

When Wireshark's WebSocket dissector processes the malicious data, the improper memory allocation handling causes the application to crash, denying the user access to their network analysis tool.

The vulnerability mechanism centers on the WebSocket protocol dissector's failure to properly validate and control memory operations during frame parsing. When processing crafted WebSocket data, the dissector encounters an unexpected state that triggers uncontrolled memory allocation, ultimately resulting in application termination. For detailed technical information, refer to the Wireshark Security Advisory WNPA-2026-44 and the GitLab Wireshark Work Item.

Detection Methods for CVE-2026-6869

Indicators of Compromise

• Wireshark process crashes when opening specific capture files containing WebSocket traffic
• Repeated application terminations during live capture of WebSocket-heavy network segments
• Error logs indicating dissector failures in the WebSocket module
• Core dump files generated from Wireshark crashes pointing to WebSocket dissector functions

Detection Strategies

• Monitor for abnormal Wireshark process terminations, especially when analyzing WebSocket traffic
• Implement endpoint detection to identify suspicious capture files being opened
• Use SentinelOne Singularity to detect and alert on repeated application crashes
• Audit network capture files before analysis using automated scanning tools

Monitoring Recommendations

• Configure application crash monitoring for Wireshark processes in enterprise environments
• Implement file integrity monitoring for capture file directories
• Deploy SentinelOne agents to detect exploitation attempts targeting analysis tools
• Review Wireshark version inventory across security operations teams to identify vulnerable installations

How to Mitigate CVE-2026-6869

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 untrusted capture files until patches are applied
• Consider using TShark with limited dissectors for analyzing untrusted captures

Patch Information

Wireshark has addressed this vulnerability in their security advisory. Users should update to the latest stable release immediately. Security teams can track the fix progress via the GitLab Wireshark Work Item. The official advisory is available at the Wireshark Security Advisory WNPA-2026-44.

Workarounds

• Disable the WebSocket protocol dissector when analyzing untrusted traffic
• Use capture filters to exclude WebSocket traffic from analysis when not needed
• Isolate Wireshark analysis to sandboxed environments for untrusted captures
• Implement network segmentation to prevent direct injection of malicious WebSocket traffic

# Disable WebSocket dissector in Wireshark preferences
# Edit ~/.config/wireshark/preferences (Linux) or %APPDATA%\Wireshark\preferences (Windows)
# Add the following line to disable the WebSocket dissector:
websocket.enable: FALSE

# Alternatively, use command-line option to disable specific dissector
wireshark --disable-protocol websocket capture.pcap