CVE-2026-96423 in Wireshark
Summary
by MITRE • 09/29/2026
X11 protocol dissector crash in 4.6.0 to 4.6.8 and 4.4.0 to 4.4.18 allows denial of service
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Analysis
by VulDB Data Team • 09/29/2026
The vulnerability identified involves a critical flaw within the X11 protocol dissector found in specific versions of network analysis software, specifically affecting releases ranging from version 4.4.0 through 4.4.18 and from 4.6.0 through 4.6.8. This issue manifests as an application crash when processing malformed or unexpectedly structured data packets associated with the X Window System protocol. The root cause of this instability lies in improper validation of input parameters during the parsing phase, where the software fails to adequately check buffer boundaries or handle edge cases within the packet structure. Consequently, when a user attempts to open a capture file containing these specific anomalous sequences, or if live traffic is analyzed under certain conditions, the application encounters an unrecoverable error leading to termination of the process. This behavior aligns with common patterns observed in memory corruption vulnerabilities where insufficient bounds checking allows for out-of-bounds reads or writes, although in this instance, it primarily results in a denial of service rather than arbitrary code execution due to the nature of the crash mechanism within the dissector logic.
From an operational perspective, this vulnerability poses a significant risk to security professionals and network administrators who rely on these tools for traffic analysis and incident response. The primary impact is a denial of service against the analytical tool itself, which can disrupt ongoing investigations or monitoring activities if malicious actors are able to inject crafted packets into monitored networks. While the immediate effect is limited to application stability, it highlights potential weaknesses in how legacy protocols like X11 are handled by modern analysis tools. Attackers could potentially exploit this weakness as part of a broader attack strategy aimed at disrupting security operations centers or hindering forensic capabilities during an active breach. The lack of robust error handling means that even non-malicious but corrupted capture files can cause the same disruption, emphasizing the importance of input sanitization in software designed to process untrusted data sources from various network environments.
To mitigate this risk, users are strongly advised to upgrade their installations to versions beyond 4.6.8 and 4.4.18 where these parsing flaws have been addressed by the development team. Until an update is applied, it is prudent to avoid opening capture files of unknown origin or those generated from untrusted network segments using the affected software versions. Implementing strict input validation policies for any custom scripts that interact with packet data can also reduce exposure. Furthermore, organizations should consider deploying these tools within sandboxed environments where a crash does not compromise host system integrity. This incident underscores the necessity of rigorous code review practices focusing on boundary checks and exception handling in protocol dissectors to prevent similar vulnerabilities classified under CWE-125 for out-of-bounds read or CWE-787 for out-of-bounds write scenarios, depending on the specific memory access pattern involved. The ATT&CK framework categorizes such disruptions as potential impacts against availability, reinforcing the need for resilient tooling in security operations to maintain continuous monitoring capabilities despite adversarial attempts to degrade analytical infrastructure.