CVE-2026-76886 in Wireshark
Summary
by MITRE • 08/20/2026
C12.22 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 as C12.22 represents a critical stability issue within the network protocol analysis software, specifically affecting versions ranging from 4.4.0 through 4.4.18 and 4.6.0 through 4.6.7. This flaw resides in the dissector responsible for parsing the C12.22 protocol, which is commonly utilized in smart grid communications and energy management systems to facilitate data exchange between utility meters and head-end systems. The core technical deficiency involves improper validation of input parameters during the deserialization process of network packets. When a specially crafted packet containing malformed or unexpectedly structured fields is processed by the dissector, it triggers an unhandled exception that leads directly to application termination. This behavior classifies the vulnerability as a classic denial of service condition, where the availability of the analysis tool is compromised without requiring any form of authentication or user interaction beyond the mere presence of malicious traffic in the monitored network segment.
From a technical perspective, this incident aligns with CWE-20 Improper Input Validation and CWE-400 Uncontrolled Resource Consumption. The dissector fails to adequately check buffer boundaries or data type integrity before attempting to access specific memory locations associated with protocol fields. In many such implementations, the lack of rigorous bounds checking allows an attacker to supply a payload that causes a segmentation fault or stack overflow within the application process. Because network analysis tools often run continuously in production environments to monitor traffic for security and performance metrics, this crash can disrupt ongoing forensic investigations, hinder real-time threat detection capabilities, and cause significant operational downtime for teams relying on these tools for visibility into critical infrastructure communications. The impact is particularly severe given that C12.22 packets are part of the foundational communication layer in many smart grid deployments, meaning an attacker could potentially trigger this crash simply by injecting a single malformed packet into the network stream being monitored.
The operational implications extend beyond simple application restarts. In enterprise environments where these tools are integrated with broader security information and event management systems or automated response platforms, a sudden crash can lead to gaps in logging and monitoring coverage. Attackers aware of this vulnerability could use it as a distraction technique to mask other malicious activities occurring on the network while administrators deal with the service disruption. Furthermore, if the tool is deployed in an inline mode rather than passive tapping, the failure could result in actual packet loss for legitimate traffic, degrading overall network performance and reliability. This scenario reflects tactics observed in advanced persistent threat campaigns where availability attacks are used to test defenses or create chaos during a broader intrusion attempt, mapping closely to ATT&CK technique T1499 Endpoint Denial of Service.
Mitigation strategies must prioritize immediate patching as the primary defense vector. Organizations running affected versions should upgrade to the latest stable release that includes the fix for this specific dissector crash. Until an update is applied, network administrators can implement temporary countermeasures at the perimeter firewall or intrusion detection system level by filtering out malformed C12.22 packets based on known bad signatures or anomaly detection rules. Additionally, deploying these analysis tools within containerized environments with automatic restart policies and resource limits can help contain the blast radius of such crashes, ensuring that a single process failure does not take down the entire monitoring infrastructure. Regular auditing of protocol parsers against evolving threat intelligence is also recommended to maintain resilience against similar input validation flaws in other dissectors used for different protocols.