CVE-2026-6531: Wireshark SANE Protocol DoS Vulnerability

CVE-2026-6531 Overview

CVE-2026-6531 is an Infinite Loop vulnerability affecting the SANE protocol dissector in Wireshark versions 4.6.0 to 4.6.4 and 4.4.0 to 4.4.14. This vulnerability allows an attacker to cause a denial of service condition by providing specially crafted network traffic or capture files that trigger an infinite loop in the SANE dissector, causing Wireshark to become unresponsive.

Critical Impact
Exploitation of this vulnerability can render Wireshark completely unresponsive, disrupting network analysis operations and potentially causing loss of captured traffic data during security investigations.

Affected Products

Wireshark 4.6.0 to 4.6.4
Wireshark 4.4.0 to 4.4.14

Discovery Timeline

2026-04-30 - CVE-2026-6531 published to NVD
2026-04-30 - Last updated in NVD database

Technical Details for CVE-2026-6531

Vulnerability Analysis

This vulnerability is classified as CWE-835 (Loop with Unreachable Exit Condition), commonly referred to as an infinite loop vulnerability. The SANE (Scanner Access Now Easy) protocol dissector in Wireshark contains a logic flaw that allows a specially crafted packet or capture file to trigger a loop condition that never terminates.

The vulnerability requires local access to exploit, meaning an attacker would need to convince a user to open a malicious capture file or process network traffic containing the exploit payload. While user interaction is required, no authentication or special privileges are needed to trigger the condition.

The impact is limited to availability—there is no compromise of confidentiality or integrity. However, in environments where Wireshark is used for live network monitoring or security incident response, a denial of service against the analysis tool could significantly impair operational capabilities.

Root Cause

The root cause lies in improper loop termination conditions within the SANE protocol dissector. When parsing certain malformed SANE protocol data, the dissector enters a loop that lacks proper bounds checking or exit conditions, causing it to iterate indefinitely. This is a classic CWE-835 vulnerability where the loop's exit condition can never be satisfied given specific input patterns.

Attack Vector

The attack vector is local, requiring user interaction to exploit. An attacker could craft a malicious PCAP file containing specially structured SANE protocol traffic and distribute it to targets. When a victim opens the file in a vulnerable version of Wireshark, the infinite loop is triggered, causing the application to hang.

Alternatively, if Wireshark is capturing live traffic that includes the malicious SANE protocol packets, the same condition could be triggered without explicitly opening a file. This makes the vulnerability particularly relevant in environments where Wireshark is used for real-time network monitoring.

The vulnerability mechanism involves malformed SANE protocol data that exploits insufficient loop boundary validation in the dissector. For detailed technical information, refer to the GitLab Issue #21139 and the Wireshark Security Advisory WNPA-SEC-2026-30.

Detection Methods for CVE-2026-6531

Indicators of Compromise

Wireshark processes consuming 100% CPU with no apparent progress in packet analysis
Wireshark application becoming unresponsive when opening specific PCAP files
SANE protocol traffic (typically TCP port 6566) with abnormal or malformed packet structures
User reports of Wireshark hanging when analyzing captures from specific sources

Detection Strategies

Monitor for Wireshark processes with unusually high CPU utilization that persist beyond normal analysis timeframes
Implement file integrity monitoring on capture file directories to detect potentially malicious PCAP files
Use application behavior monitoring to detect Wireshark entering an unresponsive state
Review Wireshark version information across endpoints to identify vulnerable installations

Monitoring Recommendations

Deploy SentinelOne Singularity XDR to monitor endpoint behavior and detect applications entering infinite loop conditions
Configure alerts for Wireshark processes that exceed CPU thresholds for extended periods
Implement centralized logging of application crashes and hangs to identify exploitation attempts
Maintain an inventory of Wireshark installations and their versions for rapid vulnerability assessment

How to Mitigate CVE-2026-6531

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 PCAP files from untrusted sources until patching is complete
Consider disabling the SANE protocol dissector if not required for analysis operations
Implement network segmentation to limit exposure to potentially malicious SANE traffic

Patch Information

Wireshark has addressed this vulnerability in updated releases. Organizations should update to the latest stable versions to remediate CVE-2026-6531. Refer to the Wireshark Security Advisory WNPA-SEC-2026-30 for official patch information and download links.

For tracking the technical details and fix, see GitLab Issue #21139.

Workarounds

Disable the SANE protocol dissector via Analyze > Enabled Protocols menu if SANE traffic analysis is not required
Use TShark with specific protocol filters to exclude SANE traffic during automated analysis
Implement capture filters to exclude TCP port 6566 (default SANE port) if applicable to your environment
Run Wireshark in sandboxed environments to contain potential denial of service impacts

bash

# Disable SANE dissector via command line
wireshark -o "sane.enable:false" capture.pcap

# Use TShark with SANE dissector disabled
tshark -o "sane.enable:false" -r capture.pcap