CVE-2026-15163: Wireshark Protocol Dissector Infinite Loop DoS Vulnerability

Technical summary

CVE-2026-15163 stems from improper loop termination logic in multiple protocol dissector implementations within Wireshark. The dissectors—which parse and decode various network protocols—do not properly validate input boundaries or implement sufficient break conditions, leading to infinite loops when processing malformed or adversarially crafted protocol data. The root cause is categorized as CWE-835 (Loop with Unreachable Exit Condition). Exploitation occurs when Wireshark attempts to dissect a specially constructed packet or pcap file; the affected dissectors enter an infinite loop, consuming CPU resources and rendering the application unresponsive. The CVSS 3.1 score of 5.5 (Medium) reflects a local attack vector, low complexity, no privilege requirement, user interaction required, and high availability impact.

Business impact

For security operations teams and forensic investigators who depend on Wireshark for incident response and packet analysis, this vulnerability introduces operational risk during critical investigations. An attacker could craft a malicious pcap file or network capture and share it with analysts, causing their Wireshark instances to crash during analysis. In a coordinated attack scenario, this could delay incident response or corrupt analysis workflows. The impact is limited to availability—no confidentiality or integrity risk—but the disruption occurs during potentially high-stakes security investigations. Organizations relying on Wireshark as a primary analysis tool should prioritize patching to avoid workflow interruption.

Affected systems

Wireshark versions 4.6.0 through 4.6.6 and 4.4.0 through 4.4.16 are vulnerable. This encompasses two active maintenance branches. Users on versions prior to 4.4.0 or current releases beyond 4.6.6 are not affected. The vulnerability affects all operating systems on which these Wireshark versions run (Windows, macOS, Linux).

Exploitability

Exploitation requires user interaction—specifically, the opening of a malicious capture file or the analysis of malicious packet data within Wireshark. An attacker cannot exploit this remotely by sending network traffic alone; they must persuade a user to open a file or view a capture. The attack does not require elevated privileges. From a practical standpoint, the barrier to exploitation is moderate: crafting malicious protocol data requires understanding of the affected dissectors, but tools and techniques to generate such payloads may already exist or be reverse-engineered. The attack surface is limited to users actively analyzing network traffic with vulnerable versions.

Remediation

Update Wireshark to a patched version. Consult the Wireshark security advisory and vendor release notes to verify the specific patch version for your branch (4.4.x or 4.6.x). As an interim control, restrict the analysis of untrusted or suspicious pcap files, and educate users not to open capture files from unknown sources. If workflow permits, consider temporary use of alternative packet analysis tools or isolated analysis environments.

Patch guidance

Verify the latest Wireshark release notes and security advisories from the official Wireshark project website for the recommended patch version for your currently deployed branch. If running 4.4.x, upgrade to the first patched release of 4.4.17 or later; if running 4.6.x, upgrade to the first patched release of 4.6.7 or later. Test patches in a non-production environment before broad deployment. Coordinate patching with your SOC or analysis team to minimize downtime during incident response operations.

Detection guidance

Wireshark will fail to respond or consume high CPU when processing a malicious capture. Monitor for: (1) Wireshark processes hanging or consuming sustained 100% CPU on a single thread with no network activity, (2) error logs from Wireshark indicating dissector failures or unexpected termination, (3) users reporting frozen Wireshark windows when opening specific files. If a malicious file is suspected, isolate the system, capture process dumps if possible, and check Wireshark version. Implement file-type filtering on endpoints to prevent automatic opening of untrusted pcap files with Wireshark.

Why prioritize this

This vulnerability merits timely remediation but is not critical. The CVSS 5.5 score and Medium severity reflect that exploitation requires user interaction and only impacts availability. However, because Wireshark is often deployed in security operations centers and forensic teams handling potentially adversarial artifacts, the risk of a deliberate malicious file being introduced into analysis workflows is non-trivial. Prioritize patching for environments where analysts regularly receive pcap files from external or untrusted sources, or where Wireshark is used in incident response. For isolated or internal-only usage, the risk is lower.

Risk score, explained

CVSS 3.1 score of 5.5 reflects: Local attack vector (user must open file locally), Low complexity (no special conditions required), No privilege requirement, User interaction required (analyst must open file), Unchanged scope, No confidentiality impact, No integrity impact, High availability impact (application hangs). The Medium severity is justified because the vulnerability can reliably deny service to analysis workflows but cannot escalate privileges, steal data, or persist on the system. The score appropriately penalizes the user-interaction requirement while crediting the high availability impact.

Frequently asked questions