CVE-2016-2376 in Pidgin
Summary
by MITRE
A buffer overflow vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent from the server could potentially result in arbitrary code execution. A malicious server or an attacker who intercepts the network traffic can send an invalid size for a packet which will trigger a buffer overflow.
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Analysis
by VulDB Data Team • 04/20/2025
The CVE-2016-2376 vulnerability represents a critical buffer overflow flaw within Pidgin's implementation of the MXIT protocol handling mechanism. This vulnerability stems from inadequate input validation and memory management practices when processing network packets from MXIT servers. The MXIT protocol is a proprietary instant messaging protocol used by certain messaging services, and Pidgin's client implementation fails to properly validate the size parameters of incoming packets before attempting to allocate memory for their processing. The flaw occurs when the application receives a malformed packet containing an oversized size field that exceeds the allocated buffer boundaries. This specific vulnerability falls under the CWE-121 category of stack-based buffer overflow conditions, where insufficient boundary checking allows attackers to overwrite adjacent memory locations. The vulnerability is particularly concerning because it can be exploited remotely through network interception or by compromising a legitimate MXIT server, making it a prime target for man-in-the-middle attacks and remote code execution exploits.
The technical exploitation of this vulnerability requires an attacker to craft malicious MXIT packets with deliberately oversized size fields that trigger the buffer overflow condition during packet processing. When Pidgin attempts to process such malformed data, the application's memory management routines fail to validate the packet size against allocated buffer dimensions, resulting in memory corruption that can be leveraged for arbitrary code execution. The attack vector operates through network traffic interception or server compromise, where an attacker can inject malicious packets into the communication stream between the client and server. This vulnerability directly maps to the ATT&CK technique T1059.007 for Command and Scripting Interpreter, as successful exploitation could enable attackers to execute arbitrary commands on the victim's system. The memory corruption typically manifests through stack smashing or heap corruption patterns that can be exploited to overwrite return addresses or function pointers, ultimately allowing attackers to redirect program execution flow and inject malicious code.
The operational impact of CVE-2016-2376 extends beyond simple remote code execution to encompass complete system compromise and data exfiltration capabilities. When successfully exploited, the vulnerability allows attackers to gain full control over the victim's Pidgin client, potentially enabling them to access all connected accounts, read messages, and perform actions on behalf of the user. The vulnerability affects any version of Pidgin that supports MXIT protocol handling, making it particularly dangerous in enterprise environments where instant messaging clients are widely deployed. Organizations using Pidgin for communication purposes face significant risk exposure, as the vulnerability can be exploited without user interaction once the malicious packet is received. The exploitability factor is enhanced by the fact that MXIT protocol support is often enabled by default in Pidgin configurations, reducing the attack surface requirements for successful exploitation. This vulnerability also poses risks to network infrastructure, as it can be leveraged to establish persistent backdoors or to conduct reconnaissance activities against internal systems.
Mitigation strategies for CVE-2016-2376 should prioritize immediate patch deployment for all affected Pidgin installations, as the vulnerability has been addressed in subsequent releases through proper input validation and memory boundary checking. Network administrators should implement traffic filtering mechanisms to prevent suspicious MXIT packets from reaching client systems, particularly when MXIT protocol support is not required for business operations. Disabling MXIT protocol support entirely in Pidgin configurations serves as an effective temporary workaround while patches are deployed. Security monitoring should focus on detecting anomalous packet sizes and malformed network traffic patterns associated with MXIT protocol communications. The implementation of network segmentation and access controls can help limit the potential impact of successful exploitation attempts. Additionally, organizations should conduct regular security assessments of their instant messaging client configurations and maintain up-to-date vulnerability management processes to ensure timely remediation of similar issues. Regular security training for users regarding the risks of connecting to untrusted messaging servers and the importance of keeping software updated remains crucial for overall security posture.