CVE-2016-2367 in Pidgin
Summary
by MITRE
An information leak 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 user, server, or man-in-the-middle can send an invalid size for an avatar which will trigger an out-of-bounds read vulnerability. This could result in a denial of service or copy data from memory to the file, resulting in an information leak if the avatar is sent to another user.
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2016-2367 represents a critical information disclosure flaw within Pidgin's implementation of the MXIT protocol handling mechanism. This issue specifically manifests when the application processes malformed avatar data transmitted through MXIT servers, creating a scenario where malicious actors can exploit the protocol's parsing logic to access memory regions beyond the intended buffer boundaries. The vulnerability stems from insufficient input validation and boundary checking within the avatar processing code, which fails to properly validate the size parameter of incoming avatar data before attempting to read or process it.
The technical exploitation of this vulnerability occurs through a carefully crafted out-of-bounds read condition that can be triggered by sending specially formatted MXIT data containing invalid avatar size parameters. When Pidgin attempts to process such malformed data, the application's memory access routines fail to properly bounds-check the avatar data size, allowing an attacker to read memory contents that extend beyond the allocated buffer space. This memory access pattern creates a potential information leak scenario where sensitive data residing in adjacent memory locations may be inadvertently exposed to the application's processing logic. The flaw operates at the protocol level within Pidgin's MXIT plugin, making it particularly dangerous as it can be exploited through legitimate communication channels without requiring special privileges or elevated access rights.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass significant security implications including potential information disclosure and data leakage. When exploited successfully, the out-of-bounds read can result in the exposure of sensitive information such as memory addresses, cryptographic keys, or other confidential data that may be stored in adjacent memory regions. The vulnerability's potential for information leakage means that data transmitted between users could be compromised, as the malicious avatar data could be processed and subsequently forwarded to other users within the network, creating a chain reaction of potential data exposure. Additionally, the vulnerability can be leveraged for denial of service attacks by causing application crashes or unpredictable behavior when the malformed data triggers memory access violations.
This vulnerability aligns with CWE-125: Out-of-bounds Read, which specifically addresses situations where applications read data beyond the boundaries of allocated buffers without proper validation. The flaw also relates to ATT&CK technique T1059.007: Command and Scripting Interpreter: Python, as the vulnerability exists within a component that handles network protocol communication, potentially allowing for indirect exploitation through network-based attacks. The MXIT protocol implementation in Pidgin demonstrates a classic example of insufficient input validation in network protocol handlers, where the application fails to implement proper bounds checking for variable-length data fields. Security practitioners should note that this vulnerability represents a common class of flaws in messaging applications where protocol parsing logic does not adequately protect against malformed input data, making it a significant concern for any application handling external protocol data.
Mitigation strategies for CVE-2016-2367 should focus on implementing robust input validation and bounds checking mechanisms within the MXIT protocol handling code. The immediate solution involves updating Pidgin to versions that contain patches addressing the specific buffer overflow condition in avatar data processing. Organizations should also implement network monitoring to detect and block malformed MXIT data packets that attempt to exploit this vulnerability. Additional protective measures include configuring network firewalls to restrict MXIT protocol traffic where possible, implementing proper error handling routines that gracefully manage invalid data, and conducting regular security assessments of messaging applications to identify similar protocol parsing vulnerabilities. The vulnerability serves as a reminder of the importance of rigorous input validation in network protocol implementations and the need for comprehensive security testing of communication components within instant messaging applications.