CVE-2026-5402: Wireshark TLS Dissector RCE Vulnerability

CVE-2026-5402 Overview

A heap-based buffer overflow vulnerability exists in the TLS protocol dissector of Wireshark versions 4.6.0 through 4.6.4. This memory corruption flaw can be triggered when processing specially crafted TLS traffic, potentially allowing attackers to cause denial of service conditions or achieve arbitrary code execution on systems running vulnerable versions of Wireshark.

Critical Impact

Network-based attackers can exploit this vulnerability to crash Wireshark or potentially execute malicious code by sending crafted TLS packets to a system capturing network traffic.

Affected Products

• Wireshark 4.6.0
• Wireshark 4.6.1 through 4.6.3
• Wireshark 4.6.4

Discovery Timeline

• 2026-04-30 - CVE CVE-2026-5402 published to NVD
• 2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-5402

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow), a dangerous memory corruption issue that occurs when data is written beyond the boundaries of allocated heap memory. The flaw resides in Wireshark's TLS protocol dissector, which is responsible for parsing and analyzing TLS-encrypted network traffic during packet capture operations.

The vulnerability requires user interaction, meaning an attacker would need to convince a user to open a malicious capture file or capture traffic containing specially crafted TLS packets. Once triggered, the heap overflow can corrupt adjacent memory structures, leading to application crashes or potentially allowing attackers to hijack program execution flow.

Network security analysts and penetration testers who regularly use Wireshark to inspect TLS traffic are particularly at risk, as they may encounter malicious packet captures during incident response or security assessments.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within the TLS protocol dissector component. When parsing certain malformed TLS handshake messages or record structures, the dissector fails to properly validate input lengths before copying data into heap-allocated buffers. This insufficient input validation allows an attacker to supply oversized data that exceeds the allocated buffer capacity, resulting in heap memory corruption.

Attack Vector

The attack can be executed over the network by sending malicious TLS packets to a network segment being monitored by Wireshark. Alternatively, an attacker can craft a malicious pcap or pcapng capture file containing the exploit payload and distribute it to targets. When the victim opens the capture file or captures live traffic containing the malicious packets, the heap overflow is triggered during TLS dissection.

The vulnerability is exploitable through crafted TLS protocol data that causes the dissector to write beyond heap buffer boundaries. Technical details regarding the specific exploitation mechanism are available in the GitLab Issue Discussion and the Wireshark Security Advisory.

Detection Methods for CVE-2026-5402

Indicators of Compromise

• Wireshark process crashes when opening specific capture files or analyzing certain TLS traffic
• Unexpected application termination with heap corruption or memory access violation errors
• Core dumps or crash logs indicating failures in the TLS dissector module
• Suspicious pcap/pcapng files with anomalous TLS record structures

Detection Strategies

• Monitor for Wireshark process crashes and correlate with recently opened capture files
• Implement file integrity monitoring on capture file directories to detect suspicious files
• Deploy endpoint detection solutions capable of identifying heap spray or overflow exploitation attempts
• Review system logs for repeated Wireshark failures associated with specific network captures

Monitoring Recommendations

• Enable crash reporting and centralized logging for Wireshark instances across the organization
• Monitor network traffic for anomalous TLS handshake patterns that may indicate exploitation attempts
• Implement application whitelisting to control which capture files can be opened
• Track Wireshark version deployments to ensure vulnerable versions are identified and remediated

How to Mitigate CVE-2026-5402

Immediate Actions Required

• Upgrade Wireshark to version 4.6.5 or later immediately
• Avoid opening capture files from untrusted sources until patched
• Disable the TLS dissector as a temporary workaround if immediate patching is not possible
• Restrict Wireshark usage to isolated analysis environments when examining untrusted traffic

Patch Information

The Wireshark development team has addressed this vulnerability in subsequent releases. Organizations should upgrade to the latest stable version to remediate this security issue. Detailed patch information and release notes are available through the Wireshark Security Advisory. For technical discussion of the fix, refer to the GitLab Issue Discussion.

Workarounds

• Disable the TLS dissector by navigating to Analyze → Enabled Protocols and unchecking TLS/SSL
• Use Wireshark's display filters to avoid processing TLS traffic from untrusted captures
• Run Wireshark in an isolated virtual machine or container when analyzing suspicious traffic
• Limit network capture operations to trusted network segments only

# Disable TLS dissector via command line
wireshark -o "tls.enabled:FALSE" capture.pcapng

# Alternatively, use tshark with dissector disabled
tshark -o "tls.enabled:FALSE" -r suspicious_capture.pcapng