CVE-2014-1509 in Firefox
Summary
by MITRE
Buffer overflow in the _cairo_truetype_index_to_ucs4 function in cairo, as used in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25, allows remote attackers to execute arbitrary code via a crafted extension that renders fonts in a PDF document.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2014-1509 represents a critical buffer overflow flaw within the cairo graphics library implementation, specifically within the _cairo_truetype_index_to_ucs4 function. This function serves as a crucial component in font handling operations, particularly when processing truetype font data within PDF documents. The flaw manifests when the cairo library processes malformed font data, creating conditions where attackers can manipulate memory allocation and execution flow through carefully crafted font extensions. The vulnerability affects multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey across their respective version ranges, making it a widespread concern for organizations relying on these applications for document rendering and display.
The technical exploitation of this vulnerability occurs through a classic buffer overflow attack pattern where insufficient bounds checking allows an attacker to write beyond allocated memory boundaries. When the _cairo_truetype_index_to_ucs4 function processes font index data, it fails to properly validate the size of incoming data structures, enabling attackers to craft malicious font extensions that trigger memory corruption. This flaw directly maps to CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows memory access beyond allocated buffers. The attack vector specifically targets PDF document rendering functionality where font data is processed, making it particularly dangerous in environments where users frequently open PDF documents from untrusted sources.
The operational impact of CVE-2014-1509 extends beyond simple code execution capabilities to encompass complete system compromise potential. Remote attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected application, typically resulting in full system compromise when users open malicious PDF documents. The vulnerability's exploitation requires no user interaction beyond opening the malicious document, making it particularly dangerous for targeted attacks against end users. Security researchers have identified this flaw as a high-risk vulnerability that aligns with ATT&CK technique T1059.007, which describes the execution of malicious code through application-specific vulnerabilities. The widespread adoption of affected Mozilla products means that organizations across various sectors remain vulnerable, including financial institutions, government agencies, and enterprise environments where PDF document processing is common.
Mitigation strategies for CVE-2014-1509 primarily focus on immediate software updates and patch management protocols. Organizations should prioritize upgrading all affected Mozilla products to their patched versions, including Firefox 28.0, Thunderbird 24.4, and SeaMonkey 2.25, which contain the necessary fixes for the buffer overflow condition. Additional defensive measures include implementing content filtering solutions that scan PDF documents for malformed font data, configuring application sandboxing to limit the potential impact of successful exploitation, and establishing network-based intrusion detection systems to monitor for exploitation attempts. Security teams should also consider deploying web application firewalls that can detect and block suspicious font data patterns. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date graphics libraries and font rendering components, as these foundational elements often remain overlooked in traditional security assessment processes. Organizations should implement comprehensive vulnerability management programs that include regular assessment of graphics libraries and font processing components to prevent similar issues from arising in the future.