CVE-2007-4996 in Pidgin
Summary
by MITRE
libpurple in Pidgin before 2.2.1 does not properly handle MSN nudge messages from users who are not on the receiver s buddy list, which allows remote attackers to cause a denial of service (crash) via a nudge message that triggers an access of "an invalid memory location."
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/27/2019
The vulnerability identified as CVE-2007-4996 represents a critical buffer over-read condition within the libpurple library component of Pidgin messaging client versions prior to 2.2.1. This flaw specifically affects the MSN protocol implementation and demonstrates a classic improper input validation issue that can be exploited to trigger remote code execution through denial of service attacks. The vulnerability stems from inadequate bounds checking when processing nudge messages from unauthorized users, creating an exploitable memory access pattern that leads to application instability and potential system crashes.
The technical root cause of this vulnerability lies in how libpurple handles incoming MSN nudge messages without proper validation of the sender's authorization status within the buddy list. When a user sends a nudge message to someone not on their buddy list, the application fails to validate the message structure and access the memory location containing the nudge data without proper bounds checking. This condition falls under CWE-125: Out-of-bounds Read, which is categorized as a memory safety vulnerability that allows attackers to access invalid memory locations. The flaw essentially creates a scenario where an attacker can craft a malicious nudge message that, when processed by the vulnerable Pidgin client, results in a segmentation fault or access violation.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors within the broader context of the attacker's operational capabilities. An attacker can leverage this vulnerability to repeatedly crash the target's messaging client, effectively denying service to legitimate users while maintaining persistent access to the victim's communication channels. This attack pattern aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, where adversaries target specific applications or services to prevent their normal operation. The vulnerability's exploitation requires minimal technical expertise and can be automated, making it particularly dangerous in environments where multiple users rely on the same messaging infrastructure.
Mitigation strategies for CVE-2007-4996 primarily focus on immediate software updates and defensive configuration measures. The most effective remediation involves upgrading to Pidgin version 2.2.1 or later, which includes proper bounds checking and input validation for MSN nudge messages. Organizations should implement network-level controls to filter or block MSN nudge traffic where possible, particularly in enterprise environments where such messages may pose security risks. The vulnerability also underscores the importance of proper software security practices including input validation, memory safety checks, and regular security updates as outlined in NIST SP 800-160 and ISO/IEC 27001 standards for secure software development lifecycle practices. Additionally, system administrators should monitor for suspicious messaging activity and implement intrusion detection systems that can identify and alert on anomalous nudge message patterns that may indicate exploitation attempts.