CVE-2026-106204 in Chrome
Summary
by MITRE • 10/06/2026
Use after free in PDF in Google Chrome prior to 155.0.8059.39 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted PDF file. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability described represents a critical memory corruption flaw within the PDF rendering engine of Google Chrome, specifically affecting versions prior to 155.0.8059.39. This issue is classified as an out-of-bounds write or use-after-free condition, which falls under the Common Weakness Enumeration category CWE-416 for Use After Free and potentially CWE-787 for Out-of-Bounds Write depending on the specific memory state at exploitation time. The root cause lies in improper management of object lifecycles within the PDF parser component. When Chrome processes a maliciously crafted PDF file, it allocates memory buffers to store parsed objects such as fonts, images, or form fields. Under normal operation, these objects are freed when they are no longer needed. However, due to a logic error in the reference counting mechanism or pointer invalidation process, certain pointers continue to reference deallocated memory regions. An attacker can exploit this by crafting a PDF that triggers specific parsing paths where an object is accessed after its underlying memory has been returned to the system allocator but before it is reallocated for another purpose.
The operational impact of this vulnerability is severe due to the potential for arbitrary code execution within the browser's sandboxed environment. Modern browsers employ strict sandboxes to isolate renderer processes from the host operating system, limiting the damage a compromised process can inflict. However, use-after-free vulnerabilities are among the most potent attack vectors because they allow an attacker to control memory layout and overwrite critical data structures such as function pointers or virtual table entries. By carefully crafting the PDF content, an attacker can manipulate these overwritten values to redirect execution flow to shellcode injected into the heap or stack. This effectively bypasses the sandbox protections if the exploit chain successfully escalates privileges from the renderer process to a higher-level context or executes code directly within the constrained environment in a way that achieves persistence or data exfiltration. The Chromium security team has rated this issue as High severity, reflecting its potential for remote code execution without user interaction beyond opening the malicious document.
From an offensive security perspective, this vulnerability aligns with several techniques documented in the MITRE ATT&CK framework. It primarily relates to T1203 Exploitation for Client Execution and potentially T1059 Command and Scripting Interpreter if the executed code invokes system commands. The attack vector is remote via a crafted PDF file, which corresponds to Initial Access through Spearphishing Attachment or Drive-by Compromise depending on how the victim encounters the malicious document. Defenders should note that such vulnerabilities often require sophisticated exploitation techniques involving heap grooming to stabilize memory layout and ensure reliable control of execution flow. This makes them particularly dangerous as they can be weaponized in targeted attacks against high-value targets who may not immediately update their browsers upon notification.
Mitigation strategies focus primarily on timely patching, as the vulnerability has been addressed in Google Chrome version 155.0.8059.39 and later releases. Organizations should enforce automated browser updates to ensure all endpoints are running patched versions of Chromium-based applications. In environments where immediate patching is not feasible, network-level controls such as web proxies or secure email gateways can be configured to inspect PDF files for known malicious patterns or structural anomalies indicative of exploitation attempts. Additionally, enabling sandbox enforcement policies and restricting the execution of scripts within browser contexts can reduce the attack surface. Security awareness training should also emphasize caution when opening PDF documents from untrusted sources, although technical controls remain the primary defense against such sophisticated memory corruption exploits. Regular vulnerability scanning and monitoring for indicators of compromise related to heap spraying or unusual process behavior in renderer processes are recommended supplementary measures.