CVE-2011-1956 in Wireshark
Summary
by MITRE
The bytes_repr_len function in Wireshark 1.4.5 uses an incorrect pointer argument, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via arbitrary TCP traffic.
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Analysis
by VulDB Data Team • 04/16/2025
The vulnerability identified as CVE-2011-1956 resides within Wireshark version 1.4.5 and specifically targets the bytes_repr_len function implementation. This flaw represents a classic null pointer dereference issue that occurs when the function receives an incorrect pointer argument during processing of TCP traffic. The vulnerability demonstrates how seemingly minor coding errors in network protocol analysis tools can lead to significant operational disruptions. The affected function operates within Wireshark's packet analysis framework where it processes byte representations for display purposes, making it a critical component in the tool's ability to parse and present network traffic data.
The technical execution of this vulnerability occurs when remote attackers craft specially formatted TCP packets that trigger the flawed bytes_repr_len function. When Wireshark processes these malicious packets, the function receives a NULL pointer as an argument instead of the expected valid memory reference, causing the application to crash upon attempting to dereference the null pointer. This type of error falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The vulnerability's impact is confined to denial of service rather than arbitrary code execution, but the consequences for network monitoring operations can be severe as it renders the network analysis tool completely unusable during the period of the crash.
From an operational standpoint, this vulnerability poses significant risks to network security operations centers and forensic analysis teams that rely on Wireshark for network traffic inspection. The remote nature of the attack means that an attacker anywhere on the network can potentially disrupt Wireshark operations without requiring local access or authentication. The application crash results in immediate service disruption, forcing analysts to restart the application and potentially lose ongoing packet capture sessions. This vulnerability aligns with ATT&CK technique T1499.004 which covers network disruption through service availability attacks, and represents a critical weakness in network monitoring tool integrity. Organizations using Wireshark for security monitoring, incident response, or network troubleshooting face immediate operational risk when this vulnerability is present.
Mitigation strategies for CVE-2011-1956 primarily involve upgrading to patched versions of Wireshark where the pointer argument handling has been corrected. The fix typically involves ensuring that the bytes_repr_len function properly validates pointer arguments before attempting to dereference them, implementing proper null checks and error handling mechanisms. Network administrators should also consider implementing network segmentation and access controls to limit exposure to potentially malicious traffic, while monitoring for unusual network behavior that might indicate exploitation attempts. Additionally, maintaining multiple analysis tools and backup monitoring solutions can provide operational resilience against similar vulnerabilities in network analysis software. The vulnerability serves as a reminder of the critical importance of input validation and proper pointer management in security tools that process untrusted network data.