CVE-2013-6478 in Pidgin
Summary
by MITRE
gtkimhtml.c in Pidgin before 2.10.8 does not properly interact with underlying library support for wide Pango layouts, which allows user-assisted remote attackers to cause a denial of service (application crash) via a long URL that is examined with a tooltip.
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Analysis
by VulDB Data Team • 06/08/2021
The vulnerability identified as CVE-2013-6478 resides within the gtkimhtml.c component of Pidgin messaging client version 2.10.7 and earlier. This flaw represents a classic buffer manipulation issue that occurs when the application processes long URLs within tooltip contexts. The vulnerability specifically manifests when Pidgin attempts to display tooltips containing extended URLs, creating a scenario where the application's interaction with the underlying Pango text rendering library becomes problematic. The issue stems from inadequate handling of wide character layouts and text processing within the GTK+ interface components that Pidgin utilizes for its HTML-based message display functionality.
The technical exploitation of this vulnerability occurs through user-assisted remote attack vectors where an attacker crafts a malicious message containing an exceptionally long URL that triggers the problematic code path. When Pidgin processes such a message and displays it in a tooltip context, the application's inability to properly manage the wide character Pango layout calculations causes a memory management failure. This results in an application crash that effectively denies service to legitimate users who may encounter such malicious content during normal chat operations. The flaw operates at the intersection of text rendering libraries and user interface components, specifically targeting how Pidgin handles tooltip display for extended URLs within its HTML input method system.
From an operational impact perspective, this vulnerability enables attackers to disrupt normal communication services through deliberate denial of service attacks. The crash occurs during tooltip processing, which means users may experience unexpected application termination when viewing messages containing crafted long URLs, potentially interrupting ongoing conversations or causing complete application instability. The vulnerability affects all versions of Pidgin prior to 2.10.8 and represents a significant security concern for users who may encounter malicious content from untrusted sources. This type of vulnerability can be particularly problematic in environments where Pidgin is used for critical communication, as it can be exploited to disrupt service availability without requiring elevated privileges or complex attack infrastructure.
The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and more specifically with CWE-129, concerning invalid access to buffer locations. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1059.008, representing command and scripting interpreter usage. The attack surface is limited to users who view the malicious content within Pidgin's tooltip functionality, making it a user-assisted rather than fully autonomous attack vector. Mitigation strategies should focus on updating to Pidgin version 2.10.8 or later, which includes patches addressing the improper interaction with Pango layout handling. Organizations should also consider implementing content filtering measures to prevent exposure to potentially malicious URLs, though the primary defense remains the software update to address the root cause of the buffer handling issue.