CVE-2016-1522 in Graphite
Summary
by MITRE
Code.cpp in Libgraphite in Graphite 2 1.2.4, as used in Mozilla Firefox before 43.0 and Firefox ESR 38.x before 38.6.1, does not consider recursive load calls during a size check, which allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly execute arbitrary code via a crafted Graphite smart font.
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Analysis
by VulDB Data Team • 10/23/2024
The vulnerability identified as CVE-2016-1522 resides within the Libgraphite library component of the Graphite 2 font rendering system, specifically in the Code.cpp file. This flaw manifests in Mozilla Firefox versions prior to 43.0 and Firefox ESR 38.x versions before 38.6.1, creating a critical security risk that affects web browsers relying on Graphite smart font technology for text rendering. The vulnerability stems from improper handling of recursive load calls during size validation processes, which creates a dangerous condition in memory management.
The technical implementation flaw occurs when the Graphite smart font processing system encounters a crafted malicious font file that triggers recursive loading operations during the size checking phase. During normal operation, the system should validate font dimensions and structure before processing, but the recursive load mechanism fails to properly track or limit these nested calls. This recursive behavior leads to excessive heap memory allocation and manipulation, ultimately resulting in heap-based buffer overflow conditions. The flaw operates at the intersection of memory safety and recursive function handling, where the system's failure to properly manage stack or heap resources creates exploitable conditions.
From an operational perspective, this vulnerability presents a significant risk to web browser security as it allows remote attackers to execute arbitrary code or cause system crashes through maliciously crafted Graphite smart fonts. The attack surface extends to any web application or website that loads fonts through Firefox browsers, making it particularly dangerous in environments where users encounter untrusted content. The potential for remote code execution means that attackers could gain complete control over affected systems, while the denial of service component can be used to disrupt services or create persistent availability issues. This vulnerability directly impacts the browser's rendering engine and font processing capabilities, creating a fundamental security weakness in the application's core functionality.
The mitigation strategy for CVE-2016-1522 requires immediate patching of affected Firefox versions to the patched releases, specifically Firefox 43.0 and Firefox ESR 38.6.1 or later. Organizations should prioritize updating their browser installations and verify that all systems using Graphite smart font rendering capabilities are protected. Additionally, implementing network-level controls to block or inspect font content from untrusted sources can provide additional defense-in-depth. The vulnerability demonstrates the importance of proper resource management in recursive function calls and highlights the need for comprehensive memory safety testing in font rendering libraries. This issue aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a classic example of improper handling of recursive calls that can lead to memory corruption vulnerabilities. The ATT&CK framework categorizes this under privilege escalation and code execution techniques, as it enables attackers to move from initial compromise to system control through memory corruption exploitation methods.