CVE-2026-6538: Wireshark BEEP Dissector DoS Vulnerability

CVE-2026-6538 Overview

A denial of service vulnerability exists in Wireshark's BEEP protocol dissector. The vulnerability affects Wireshark versions 4.6.0 through 4.6.4 and 4.4.0 through 4.4.14. When processing malformed BEEP protocol traffic, the dissector experiences a stack-based buffer overflow (CWE-121) that causes the application to crash, resulting in denial of service.

Critical Impact
An attacker can cause Wireshark to crash by injecting specially crafted BEEP protocol packets into network traffic being analyzed, disrupting network forensics and security monitoring operations.

Affected Products

Wireshark 4.6.0 to 4.6.4
Wireshark 4.4.0 to 4.4.14

Discovery Timeline

2026-04-30 - CVE-2026-6538 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-6538

Vulnerability Analysis

This vulnerability is classified as a stack-based buffer overflow (CWE-121) within the BEEP (Blocks Extensible Exchange Protocol) dissector component of Wireshark. The BEEP protocol dissector is responsible for parsing and displaying BEEP protocol frames captured during network analysis. When the dissector encounters specially crafted or malformed BEEP protocol data, it fails to properly validate input boundaries before writing to a stack-allocated buffer.

The vulnerability requires local access, meaning an attacker must either convince a user to open a malicious capture file or inject crafted packets into traffic being actively captured. User interaction is required, as the victim must actively use Wireshark to analyze the malicious traffic. While the vulnerability does not lead to information disclosure or code execution, it reliably causes the application to crash, terminating any ongoing packet capture or analysis session.

Root Cause

The root cause lies in insufficient bounds checking within the BEEP protocol dissector's parsing logic. When processing BEEP frames, the dissector allocates a fixed-size buffer on the stack and copies data without adequately verifying that the input data length does not exceed the buffer's capacity. This allows an attacker to craft BEEP protocol data that overflows the stack buffer, corrupting adjacent stack memory and triggering a crash.

Attack Vector

The attack vector is local, requiring either:

Malicious Capture File: An attacker crafts a PCAP or PCAPNG file containing malformed BEEP protocol packets and distributes it to a victim (via email, file sharing, etc.). When the victim opens the file in Wireshark, the BEEP dissector processes the malformed data and crashes.
Live Traffic Injection: If an attacker has network access to inject packets into traffic being actively captured by Wireshark, they can send malformed BEEP protocol packets that trigger the crash during live analysis.

The vulnerability is particularly concerning in security operations environments where analysts routinely open capture files from untrusted sources or monitor potentially hostile network traffic. A crash during a critical investigation could result in loss of unsaved analysis work and temporary blindness to network activity.

For detailed technical information, refer to the GitLab Wireshark Issue and the Wireshark Security Advisory WNPA-SEC-2026-23.

Detection Methods for CVE-2026-6538

Indicators of Compromise

Wireshark application crashes when opening specific capture files or during live capture sessions
Crash reports or core dumps indicating stack corruption in BEEP dissector functions
Unusual or malformed BEEP protocol traffic in capture files from untrusted sources

Detection Strategies

Monitor for repeated Wireshark crashes on analyst workstations, particularly when processing capture files from external sources
Implement file integrity monitoring on capture files to detect potential tampering
Use application crash monitoring tools to collect and analyze Wireshark crash dumps for patterns consistent with this vulnerability
Deploy network sensors to detect anomalous BEEP protocol traffic that may indicate exploitation attempts

Monitoring Recommendations

Enable crash reporting for Wireshark installations across the organization to quickly identify potential exploitation attempts
Review Wireshark version inventory across all systems to identify vulnerable installations
Implement centralized logging for security analyst workstations to correlate crashes with file access events

How to Mitigate CVE-2026-6538

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)
Exercise caution when opening capture files from untrusted sources until patches are applied
Consider temporarily disabling the BEEP protocol dissector if BEEP protocol analysis is not required
Review and restrict which users have Wireshark installed and limit access to capture file repositories

Patch Information

Wireshark has released security patches addressing this vulnerability. Refer to the Wireshark Security Advisory WNPA-SEC-2026-23 for official patch details and updated versions. Users should upgrade to the latest available version in their respective release branch to obtain the fix.

Workarounds

Disable the BEEP protocol dissector by navigating to Analyze → Enabled Protocols and unchecking BEEP
Use TShark in non-interactive mode with protocol filtering to exclude BEEP when processing untrusted captures
Implement network segmentation to prevent injection of malicious traffic into monitored network segments
Pre-screen capture files using automated tools before manual analysis in Wireshark

bash

# Disable BEEP dissector via command line
tshark -o "beep.enabled:FALSE" -r capture.pcap

# Alternatively, create a disabled_protos file
echo "beep" >> ~/.config/wireshark/disabled_protos