CVE-2016-2373 in Pidgin
Summary
by MITRE
A denial of service vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in an out-of-bounds read. A malicious server or user can send an invalid mood to trigger this vulnerability.
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Analysis
by VulDB Data Team • 04/20/2025
The CVE-2016-2373 vulnerability represents a critical denial of service flaw within the Pidgin instant messaging client's handling of the MXIT protocol. This vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize incoming MXIT protocol data, particularly mood information transmitted from servers or malicious users. The MXIT protocol, which is used for communication with the MXIT messaging service, lacks robust boundary checking in its data parsing routines, creating an exploitable condition that can be leveraged by attackers to disrupt service availability. The vulnerability specifically manifests when the client processes malformed mood data structures that exceed expected buffer boundaries, leading to memory access violations that cause the application to crash or become unresponsive.
The technical execution of this vulnerability involves an out-of-bounds read condition that occurs during the processing of specially crafted MXIT mood data packets. When Pidgin receives invalid mood information from an MXIT server or malicious peer, the client's protocol handler attempts to parse this data without sufficient bounds checking, resulting in memory access beyond allocated buffer limits. This type of vulnerability falls under the CWE-125 Out-of-bounds Read category, which is classified as a memory safety issue in the Common Weakness Enumeration catalog. The flaw operates at the application layer protocol handling level, where the client fails to validate the length and structure of incoming mood data before attempting to process it, making it susceptible to exploitation through crafted malicious payloads.
The operational impact of CVE-2016-2373 extends beyond simple service disruption to potentially compromise user experience and system availability within messaging environments. When exploited successfully, this vulnerability can cause Pidgin clients to crash repeatedly, forcing users to restart their messaging applications and potentially interrupting ongoing communications. In enterprise or organizational settings where Pidgin is used for business communications, such denial of service conditions can significantly impact productivity and reliability of messaging infrastructure. The vulnerability is particularly concerning because it can be triggered by malicious servers or users within the same network, meaning that even trusted communication partners could potentially exploit this weakness to disrupt service for other users. The attack vector requires minimal sophistication and can be executed remotely, making it an attractive target for attackers seeking to disrupt messaging services.
Mitigation strategies for CVE-2016-2373 should focus on both immediate patching and defensive configuration measures. The primary solution involves updating Pidgin to versions that include proper input validation and bounds checking for MXIT protocol data handling, which addresses the root cause of the vulnerability. System administrators should implement network-level filtering to prevent unauthorized MXIT protocol traffic from reaching vulnerable client systems, particularly in environments where MXIT protocol support is not required. Additionally, users should be educated about the risks of connecting to untrusted MXIT servers or accepting data from unknown sources. The vulnerability's classification under ATT&CK technique T1499.004 (Endpoint Denial of Service) highlights the importance of implementing comprehensive endpoint security measures that can detect and prevent such exploitation attempts. Organizations should also consider disabling MXIT protocol support entirely in Pidgin installations where it is not essential for business operations, providing a definitive defense against this specific attack vector while maintaining overall system functionality.