CVE-2007-4999 in Pidgin
Summary
by MITRE
libpurple in Pidgin 2.1.0 through 2.2.1, when using HTML logging, allows remote attackers to cause a denial of service (NULL dereference and application crash) via a message that contains invalid HTML data, a different vector than CVE-2007-4996.
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Analysis
by VulDB Data Team • 07/31/2019
The vulnerability identified as CVE-2007-4999 affects libpurple, the core library underlying the Pidgin instant messaging client version 2.1.0 through 2.2.1. This issue specifically manifests when the application employs HTML logging functionality, creating a distinct attack vector from CVE-2007-4996 that targets the handling of malformed HTML content within chat messages. The flaw represents a critical security concern that undermines the stability and reliability of the messaging platform.
The technical implementation of this vulnerability stems from insufficient input validation within the HTML parsing routines of libpurple. When processing chat messages containing malformed or invalid HTML data, the application fails to properly sanitize or handle these malformed elements, leading to a NULL pointer dereference condition. This occurs because the HTML parser attempts to access memory locations that have not been properly initialized or allocated, resulting in an application crash that terminates the messaging service. The vulnerability operates at the level of the application's user interface rendering engine, specifically targeting how HTML content is processed and displayed within the chat logging system.
From an operational perspective, this vulnerability presents a significant denial of service risk that can be exploited by remote attackers without requiring any privileged access or authentication. The attack requires only the ability to send a specially crafted message containing invalid HTML data to a victim using an affected version of Pidgin. The impact extends beyond simple service disruption as it can potentially be used to create persistent availability issues for users, particularly in environments where continuous communication is critical. Network administrators and security teams must consider this vulnerability as a potential vector for service interruption attacks that could affect enterprise communications infrastructure.
The vulnerability aligns with CWE-476, which describes NULL pointer dereference conditions in software applications, and represents a classic example of improper input validation that leads to application instability. From an adversary perspective, this vulnerability maps to ATT&CK technique T1499.004, which involves network disruption through denial of service attacks. The attack surface is particularly concerning given that HTML logging is a common feature in modern messaging applications, making this vulnerability potentially exploitable in various communication environments. Organizations should prioritize patching this vulnerability as it can be leveraged to create persistent service availability issues that may impact business continuity and user productivity.
Mitigation strategies should focus on immediate patch deployment for all affected Pidgin installations, with particular emphasis on systems that rely heavily on HTML logging functionality. Network administrators should implement message filtering mechanisms to prevent malformed HTML content from reaching vulnerable clients, while security monitoring systems should be configured to detect unusual application crash patterns that may indicate exploitation attempts. Additionally, organizations should consider implementing application sandboxing techniques to limit the impact of potential exploitation and establish incident response procedures specifically addressing denial of service vulnerabilities in communication applications.