CVE-2011-4602 in Pidgin
Summary
by MITRE
The XMPP protocol plugin in libpurple in Pidgin before 2.10.1 does not properly handle missing fields in (1) voice-chat and (2) video-chat stanzas, which allows remote attackers to cause a denial of service (application crash) via a crafted message.
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Analysis
by VulDB Data Team • 11/28/2021
The vulnerability identified as CVE-2011-4602 represents a critical denial of service flaw within the libpurple library's XMPP protocol implementation used by Pidgin instant messaging clients. This issue specifically affects versions prior to 2.10.1 and stems from inadequate input validation mechanisms when processing voice-chat and video-chat stanzas in the Extensible Messaging and Presence Protocol. The flaw manifests when the application encounters malformed or incomplete stanzas that lack required field elements, causing the client to crash upon attempting to process these malformed messages.
The technical nature of this vulnerability places it squarely within CWE-476, which describes NULL pointer dereference conditions that occur when software attempts to access memory locations through null pointers. In this case, the XMPP plugin in libpurple fails to properly validate the presence of essential fields within voice and video chat stanzas before attempting to access their contents. When remote attackers craft malicious messages that omit critical fields such as session identifiers, media stream parameters, or codec specifications, the plugin's processing logic encounters null or undefined references that result in application termination.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates an avenue for remote attackers to systematically crash Pidgin clients without requiring authentication or specialized privileges. Attackers can exploit this weakness by sending crafted XMPP stanzas to victims who are using affected versions of Pidgin, potentially leading to widespread client instability in environments where multiple users are communicating through XMPP-based networks. This vulnerability particularly affects collaborative environments where voice and video conferencing are utilized, as the attack surface increases with the number of communication channels available.
From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks targeting specific applications. The flaw demonstrates characteristics of T1595.001, where adversaries gather information about target applications to identify potential attack vectors. The exploitation requires minimal technical expertise, making it attractive to threat actors seeking to disrupt communications. Organizations using Pidgin for enterprise communications or those relying on XMPP-based services for collaboration face significant risk, as this vulnerability can be leveraged to create persistent service disruptions that impact business continuity and user productivity.
The recommended mitigation strategy involves upgrading to Pidgin version 2.10.1 or later, which includes proper input validation and error handling for XMPP voice and video chat stanzas. System administrators should also implement network-level filtering to monitor and block suspicious XMPP traffic patterns, though this approach provides only partial protection since the vulnerability can be exploited through various message formats. Additionally, users should be educated about the risks of accepting messages from untrusted sources and should avoid engaging with suspicious communications that might contain crafted stanzas designed to trigger the vulnerability.