CVE-2026-6519: Wireshark MBIM Protocol DoS Vulnerability

CVE-2026-6519 Overview

CVE-2026-6519 is an Infinite Loop vulnerability affecting the MBIM (Mobile Broadband Interface Model) protocol dissector in Wireshark versions 4.6.0 through 4.6.4 and 4.4.0 through 4.4.14. This vulnerability allows attackers to cause a denial of service condition by crafting malicious network capture files that trigger an infinite loop when processed by the vulnerable dissector.

Critical Impact
Successful exploitation can render Wireshark unresponsive, disrupting network analysis workflows and potentially affecting security monitoring operations that depend on packet capture 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-2026-6519 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-6519

Vulnerability Analysis

The vulnerability resides in the MBIM protocol dissector component of Wireshark, a widely-used network protocol analyzer. MBIM is a protocol specification used for mobile broadband devices and is commonly found in USB networking equipment. When Wireshark attempts to parse malformed MBIM protocol data, the dissector enters an infinite loop condition (CWE-835), consuming CPU resources indefinitely and causing the application to become unresponsive.

This type of vulnerability is particularly concerning in environments where Wireshark is used for automated packet analysis or as part of security monitoring infrastructure, as the denial of service could create blind spots in network visibility.

Root Cause

The root cause is classified as CWE-835: Loop with Unreachable Exit Condition (Infinite Loop). The MBIM dissector fails to properly validate loop termination conditions when processing certain malformed packets. This allows an attacker to craft input that causes the dissector to iterate indefinitely without ever reaching a valid exit condition, resulting in complete CPU resource consumption by the Wireshark process.

Attack Vector

The attack requires local access, meaning an attacker must convince a user to open a malicious packet capture file (such as a .pcap or .pcapng file) containing the crafted MBIM protocol data. While this requires user interaction, the attack is low complexity and requires no special privileges. Attack scenarios include:

Sending a malicious capture file via email or file sharing
Hosting malicious captures on websites frequented by network analysts
Compromising legitimate packet capture repositories
Including malicious packets in network forensics evidence

The vulnerability can be triggered through Wireshark's graphical interface or when using command-line tools like tshark for automated analysis, potentially impacting CI/CD pipelines and security automation.

Detection Methods for CVE-2026-6519

Indicators of Compromise

Wireshark or tshark processes consuming 100% CPU for extended periods
Application hangs when opening specific .pcap or .pcapng files
MBIM protocol data present in capture files from untrusted sources
Unusual memory growth patterns in Wireshark processes during file analysis

Detection Strategies

Monitor for Wireshark processes with abnormally high CPU utilization exceeding expected analysis timeframes
Implement file analysis sandboxing for untrusted packet captures before opening in production environments
Deploy endpoint detection rules for process anomalies related to wireshark.exe or tshark processes
Use SentinelOne's behavioral AI to detect infinite loop patterns and resource exhaustion attacks

Monitoring Recommendations

Configure process monitoring to alert on Wireshark CPU usage exceeding thresholds for extended periods
Establish baseline metrics for typical packet analysis operations to identify anomalous behavior
Log and review sources of all packet capture files opened in security-sensitive environments
Implement automated termination policies for analysis processes that exceed expected execution times

How to Mitigate CVE-2026-6519

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 packet capture files from untrusted or unknown sources
Implement organizational policies for vetting capture files before analysis
Consider running Wireshark analysis in isolated environments for untrusted files

Patch Information

Security patches addressing this vulnerability are documented in the Wireshark Security Advisory WNPA-SEC-2026-41. Additional technical details regarding the fix can be found in the GitLab Work Item #21184. Users should update to the latest stable release through their package manager or by downloading directly from the official Wireshark website.

Workarounds

Disable the MBIM protocol dissector if not required for analysis: Navigate to Analyze → Enabled Protocols and uncheck MBIM
Use command-line options to exclude MBIM dissection: tshark --disable-protocol mbim
Process untrusted captures in sandboxed virtual machines with resource limits and automatic termination
Implement timeout mechanisms when running automated packet analysis workflows
Configure operating system resource limits to prevent single processes from consuming all available CPU

bash

# Configuration example
# Disable MBIM protocol dissector via preferences file
# Add to ~/.config/wireshark/preferences (Linux) or %APPDATA%\Wireshark\preferences (Windows)
echo "mbim.enabled: FALSE" >> ~/.config/wireshark/disabled_protos

# Alternative: Run tshark with MBIM dissector disabled
tshark -r suspicious_capture.pcap --disable-protocol mbim

# Set process resource limits on Linux before running analysis
ulimit -t 300  # Limit CPU time to 300 seconds
wireshark suspicious_capture.pcap