CVE-2026-76918 in Wireshark
Summary
by MITRE • 08/20/2026
SSH protocol dissector crash in 4.6.0 to 4.6.7 and 4.4.0 to 4.4.18 allows denial of service
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified involves a critical flaw within the Secure Shell protocol dissector, specifically affecting software versions ranging from 4.6.0 through 4.6.7 and 4.4.0 through 4.4.18. This issue manifests as an application crash triggered by malformed or specially crafted SSH traffic processed during network packet analysis. The root cause lies in the improper handling of specific data structures within the dissector logic, where input validation mechanisms fail to adequately check for boundary conditions or unexpected payload sizes before attempting memory allocation or pointer dereferencing operations. This lack of robust error handling allows an attacker who can inject malicious packets into a monitored network segment to induce a segmentation fault or similar fatal exception in the analyzing application.
From a technical perspective, this flaw aligns with CWE-125, Out-of-bounds Read, and potentially CWE-400, Uncontrolled Resource Consumption, depending on whether the crash results from reading invalid memory addresses or exhausting system resources during malformed packet processing. The dissector is designed to parse binary protocols for visibility into network communications, but when it encounters a payload that deviates significantly from expected SSH protocol specifications without proper sanitization checks, it proceeds with unsafe operations. This behavior exposes the underlying application logic to exploitation by any entity capable of sending crafted packets to the affected system, particularly in environments where automated packet capture and analysis tools are deployed for security monitoring or troubleshooting purposes.
The operational impact of this vulnerability is primarily centered on denial of service conditions within network diagnostic and security monitoring infrastructure. When a dissector crashes due to malicious input, it disrupts continuous traffic analysis capabilities, potentially creating blind spots during active attacks or incident response scenarios. For organizations relying on these tools for real-time threat detection, the crash can lead to significant gaps in visibility, allowing adversarial activities such as lateral movement, data exfiltration, or command and control communications to go undetected until manual intervention occurs. Furthermore, repeated crashes may degrade system stability over time if not properly managed by wrapper processes that restart the application upon failure.
Mitigation strategies should prioritize immediate patching of all affected software versions to 4.6.8 or later, as well as version 4.4.19 and beyond, where these input validation flaws have been addressed in upstream releases. In environments where upgrading is not immediately feasible, network segmentation controls can be implemented to restrict access to the vulnerable systems from untrusted networks. Additionally, deploying intrusion prevention systems configured with signatures for malformed SSH packets may help filter out malicious traffic before it reaches the dissector engine. Security teams should also consider implementing automated restart mechanisms or resource limits to minimize downtime in case of recurrence while awaiting permanent remediation efforts aligned with industry best practices for secure software development lifecycle integration.