CVE-2026-5408 Overview
CVE-2026-5408 is a denial of service vulnerability affecting the BT-DHT protocol dissector in Wireshark versions 4.6.0 through 4.6.4 and 4.4.0 through 4.4.14. The vulnerability stems from improper handling of uncontrolled recursion (CWE-674), which can cause Wireshark to crash when processing specially crafted network traffic or capture files containing malicious BT-DHT protocol packets.
Critical Impact
An attacker can cause Wireshark to crash by sending malformed BT-DHT protocol data, resulting in denial of service for network administrators and security analysts relying on the tool for traffic analysis.
Affected Products
- Wireshark 4.6.0 to 4.6.4
- Wireshark 4.4.0 to 4.4.14
Discovery Timeline
- 2026-04-30 - CVE-2026-5408 published to NVD
- 2026-04-30 - Last updated in NVD database
Technical Details for CVE-2026-5408
Vulnerability Analysis
This vulnerability resides in the BT-DHT (BitTorrent Distributed Hash Table) protocol dissector component of Wireshark. The BT-DHT dissector is responsible for parsing and displaying DHT protocol messages used in BitTorrent peer-to-peer networks for distributed peer discovery.
The root cause is classified as CWE-674 (Uncontrolled Recursion), indicating that the dissector fails to properly limit recursive processing when handling nested or specially structured BT-DHT protocol data. When the dissector encounters maliciously crafted input, it can enter an uncontrolled recursive state that exhausts stack memory, leading to application crash.
This is a local attack vector vulnerability, meaning exploitation requires the victim to open a malicious packet capture file or capture live traffic containing the exploit payload. Network security analysts who routinely analyze untrusted capture files are particularly at risk.
Root Cause
The vulnerability is caused by uncontrolled recursion (CWE-674) in the BT-DHT protocol dissector. The dissector lacks adequate bounds checking or recursion depth limits when processing BT-DHT protocol messages that contain deeply nested or self-referential data structures. This allows an attacker to craft packets that trigger excessive recursive function calls, eventually causing a stack overflow and application crash.
Attack Vector
Exploitation requires local access, typically through one of the following scenarios:
Malicious capture file: An attacker distributes a crafted .pcap or .pcapng file containing malicious BT-DHT packets. When a victim opens this file in Wireshark, the application crashes.
Live traffic capture: An attacker on the same network sends specially crafted BT-DHT packets while the victim is capturing traffic. The dissector crashes when processing the malicious packets.
Network forensics scenario: Security analysts investigating network incidents may encounter malicious capture files designed to prevent analysis by crashing their tools.
The vulnerability mechanism involves crafting BT-DHT protocol messages with structures that cause the dissector to recursively process data without proper termination conditions. For technical details regarding the specific implementation flaw, refer to the GitLab Issue Report and the Wireshark Security Advisory.
Detection Methods for CVE-2026-5408
Indicators of Compromise
- Wireshark application crashes when opening specific capture files or during live capture sessions
- Stack overflow errors or segmentation faults in Wireshark logs related to the BT-DHT dissector
- Capture files containing abnormally nested BT-DHT protocol structures
- Repeated Wireshark crashes when analyzing BitTorrent-related network traffic
Detection Strategies
- Monitor for Wireshark crashes associated with BT-DHT protocol dissection in application logs
- Implement file integrity monitoring for capture files in shared analysis environments
- Use automated scanning tools to identify capture files with suspicious BT-DHT message structures before opening in Wireshark
- Configure endpoint detection solutions to alert on repeated Wireshark application crashes
Monitoring Recommendations
- Track Wireshark version deployments across the organization to identify systems running vulnerable versions
- Establish baseline crash rates for analysis tools to detect anomalous crash patterns
- Monitor for distribution of untrusted capture files within the organization
How to Mitigate CVE-2026-5408
Immediate Actions Required
- Upgrade Wireshark to version 4.6.5 or later (for 4.6.x branch) or 4.4.15 or later (for 4.4.x branch)
- Avoid opening capture files from untrusted sources until patched
- Consider using alternative analysis tools for untrusted captures until the update is applied
- Review and validate capture files before analysis in production environments
Patch Information
The Wireshark development team has addressed this vulnerability in subsequent releases. Users should update to the latest stable version that includes the fix for the BT-DHT dissector recursion issue. For detailed patch information and download links, refer to the Wireshark Security Advisory.
Workarounds
- Disable the BT-DHT protocol dissector if BT-DHT analysis is not required: Navigate to Analyze → Enabled Protocols and disable bt-dht
- Use TShark with -d options to exclude BT-DHT dissection when processing untrusted captures
- Implement sandboxing for Wireshark when analyzing untrusted network captures
- Process suspicious capture files in isolated virtual environments to contain potential crashes
# Disable BT-DHT dissector via command line
tshark -r suspicious.pcap --disable-protocol bt-dht
# Alternative: Use editcap to filter out UDP port 6881 (common DHT port) before analysis
editcap -r suspicious.pcap filtered.pcap '!(udp.port == 6881)'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
