CVE-2016-5203 in Chrome
Summary
by MITRE
A use after free in PDFium in Google Chrome prior to 55.0.2883.75 for Mac, Windows and Linux, and 55.0.2883.84 for Android allowed a remote attacker to potentially exploit heap corruption via a crafted PDF file.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability CVE-2016-5203 represents a critical use after free condition within PDFium, the PDF rendering engine integrated into Google Chrome browser across multiple platforms. This flaw exists in versions prior to 55.0.2883.75 for Mac, Windows, and Linux systems, as well as 55.0.2883.84 for Android devices, creating a significant security risk for users who interact with PDF documents. The vulnerability stems from improper memory management during PDF processing, specifically when handling certain malformed or crafted PDF files that trigger memory deallocation followed by subsequent access to freed memory regions.
The technical implementation of this vulnerability involves PDFium's handling of memory allocation and deallocation processes when parsing complex PDF objects. When a maliciously crafted PDF file is processed, the engine may free a memory block while still maintaining references to it, creating a use after free condition that allows attackers to manipulate heap memory. This condition occurs during the parsing of PDF content streams or object structures where memory is allocated for processing but not properly tracked during the object lifecycle. The flaw falls under CWE-416, which specifically addresses use after free vulnerabilities, and aligns with ATT&CK technique T1059.007 for execution through PDF files. The memory corruption resulting from this condition can be exploited to execute arbitrary code with the privileges of the Chrome process, potentially leading to complete system compromise.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables remote code execution without requiring user interaction beyond opening a malicious PDF document. Attackers can craft PDF files that trigger the specific memory management flaw, allowing them to overwrite critical memory locations and inject malicious code into the Chrome process. This vulnerability particularly affects users who frequently encounter PDF documents from untrusted sources, including email attachments, web downloads, or document sharing platforms. The cross-platform nature of the vulnerability means that organizations with diverse operating system environments must implement coordinated patching strategies across all supported platforms, as the same exploit could potentially work against multiple operating systems simultaneously.
Mitigation strategies for CVE-2016-5203 primarily focus on immediate patch deployment and enhanced security configurations. Organizations should prioritize updating all Chrome installations to versions 55.0.2883.75 or later for desktop platforms and 55.0.2883.84 for Android devices, as these releases contain the necessary memory management fixes. Additional protective measures include implementing strict PDF file handling policies, enabling sandboxing features within Chrome, and deploying content filtering solutions that can detect and block suspicious PDF content. Security teams should also consider implementing network-based intrusion detection systems that can identify potential exploitation attempts through anomalous PDF processing patterns. The vulnerability demonstrates the critical importance of proper memory management in security-critical applications and underscores the necessity of regular security updates and comprehensive vulnerability management programs. Organizations should also consider implementing application whitelisting policies that restrict PDF processing to trusted applications and validate all PDF content through multiple security layers before allowing user interaction.