CVE-2026-6520 in Wireshark
Summary
by MITRE • 04/30/2026
OpenFlow v6 protocol dissector infinite loop in Wireshark 4.6.0 to 4.6.4 and 4.4.0 to 4.4.14 allows denial of service
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Analysis
by VulDB Data Team • 06/03/2026
The vulnerability resides in the OpenFlow protocol dissector implementation within Wireshark versions ranging from 4.4.0 through 4.4.14 and 4.6.0 through 4.6.4. This issue manifests as an infinite loop condition that occurs during packet analysis when processing specifically crafted OpenFlow v6 protocol traffic. The flaw represents a classic denial of service vulnerability where the dissector enters an unbounded loop, consuming excessive CPU resources and preventing normal packet processing operations. The OpenFlow protocol is commonly used in software-defined networking environments to enable communication between network switches and controllers, making this vulnerability particularly concerning for network infrastructure monitoring and analysis tools.
The technical root cause stems from inadequate input validation within the dissector's parsing logic for OpenFlow v6 messages. When Wireshark encounters malformed or specially crafted OpenFlow packets containing recursive or self-referential structures, the dissector's internal parsing functions fail to properly terminate their execution loops. This condition typically occurs when processing nested structures or when packet headers contain values that trigger iterative processing without proper termination conditions. The vulnerability is classified under CWE-835, which specifically addresses infinite loops in software implementations, and aligns with ATT&CK technique T1499.001 for network denial of service attacks. The dissector's failure to implement proper bounds checking or recursion limits creates an exploitable path where an attacker can construct malicious OpenFlow packets that will cause Wireshark to enter continuous loop execution.
The operational impact of this vulnerability extends beyond simple resource exhaustion, potentially compromising network monitoring capabilities and system availability. When an attacker successfully triggers this infinite loop condition, Wireshark becomes unresponsive and unable to process additional packets until manually terminated or the system resources are exhausted. This affects network administrators who rely on Wireshark for real-time traffic analysis, troubleshooting, and security monitoring. The vulnerability particularly impacts environments where OpenFlow traffic is prevalent such as data centers using software-defined networking solutions, network security appliances, and network infrastructure analysis tools. Organizations using affected Wireshark versions may experience complete disruption of network analysis capabilities, potentially leading to missed security events or network troubleshooting failures during critical incidents.
Mitigation strategies should prioritize immediate version updates to Wireshark 4.4.15 or 4.6.5, which contain patches addressing the infinite loop condition in the OpenFlow dissector. Network administrators should also implement network segmentation and access controls to limit exposure to potentially malicious OpenFlow traffic, particularly in environments where untrusted network sources may exist. Additionally, implementing monitoring solutions that can detect abnormal CPU utilization patterns in network analysis tools can help identify exploitation attempts. The patch addresses the core parsing logic by introducing proper loop termination conditions and input validation checks that prevent recursive structures from causing indefinite execution. Organizations should also consider implementing network access control lists or firewalls to filter OpenFlow traffic at network boundaries, reducing the attack surface for this specific vulnerability while maintaining legitimate network monitoring capabilities.