CVE-2009-1194 in pango
Summary
by MITRE
Integer overflow in the pango_glyph_string_set_size function in pango/glyphstring.c in Pango before 1.24 allows context-dependent attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a long glyph string that triggers a heap-based buffer overflow, as demonstrated by a long document.location value in Firefox.
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Analysis
by VulDB Data Team • 08/11/2021
The vulnerability identified as CVE-2009-1194 represents a critical integer overflow flaw within the Pango text rendering library that affects applications relying on this component for graphical text display. This issue exists in the pango_glyph_string_set_size function located in pango/glyphstring.c, where the library fails to properly validate input parameters before performing arithmetic operations that could result in integer overflow conditions. The vulnerability specifically impacts Pango versions prior to 1.24, making it a significant concern for systems that have not been updated with the latest security patches. The flaw manifests when processing glyph strings that exceed normal operational parameters, creating conditions where the application's memory management becomes compromised.
The technical exploitation of this vulnerability occurs through carefully crafted input that triggers a heap-based buffer overflow during the glyph string processing phase. When the pango_glyph_string_set_size function receives a malformed or excessively long glyph string, the integer overflow condition causes the memory allocation calculations to produce incorrect values that exceed the bounds of allocated heap memory. This overflow can result in memory corruption that manifests as application crashes or potentially more severe consequences including arbitrary code execution. The vulnerability demonstrates particular relevance in web browser environments where document.location values can be manipulated to trigger the problematic code path, as demonstrated in Firefox exploitation scenarios.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution in vulnerable environments. Attackers can leverage this flaw to cause application instability, leading to system crashes that disrupt user experience and potentially provide opportunities for more sophisticated attacks. The heap-based buffer overflow creates conditions where memory corruption can be manipulated to alter program execution flow, particularly when the affected application lacks proper input validation and memory protection mechanisms. This vulnerability affects not only web browsers but any application that utilizes Pango for text rendering, including desktop applications, document viewers, and system utilities that depend on proper text handling capabilities.
Mitigation strategies for CVE-2009-1194 primarily focus on immediate remediation through software updates and patches provided by the Pango development community. Organizations should prioritize upgrading to Pango version 1.24 or later, which includes the necessary fixes to address the integer overflow condition in the glyph string processing functions. Additionally, implementing input validation mechanisms at application layers can provide defensive measures against malformed glyph strings, though these should not be considered primary defenses given the underlying library vulnerability. Network-level protections such as web application firewalls may offer some detection capabilities for suspicious glyph string patterns, though these solutions remain secondary to proper software patching. The vulnerability aligns with CWE-190, which describes integer overflow conditions, and represents a classic example of how buffer overflow vulnerabilities in system libraries can create widespread security risks across multiple applications. This issue also correlates with ATT&CK technique T1059, which covers command and script injection, as the potential for arbitrary code execution through memory corruption represents a significant escalation path for attackers seeking persistent access to compromised systems.