CVE-2026-121185 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in PictureInPicture in Google Chrome prior to 157.0.8103.38 allowed a remote attacker leveraging social engineering to execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free condition within the PictureInPicture module of Google Chrome prior to version 157.0.8103.38 represents a critical memory corruption flaw that undermines the browser's sandboxing mechanisms. This specific class of error occurs when the application attempts to access memory that has already been freed by the system, leading to undefined behavior that can be exploited for malicious purposes. In this context, the PictureInPicture feature, which allows users to view video content in a floating window while interacting with other applications or web pages, contains logic errors related to object lifecycle management. When an HTML page triggers specific interactions involving picture-in-picture windows, the underlying Chromium engine may deallocate internal data structures prematurely while references to those objects remain active within the execution context. This discrepancy creates a window of opportunity for attackers to manipulate memory states in ways that were not intended by the software developers.
From a technical perspective, this flaw falls under the Common Weakness Enumeration category CWE-416, which defines use-after-free vulnerabilities as conditions where pointers are used after they have been freed. The exploitation vector relies heavily on social engineering tactics, requiring the victim to visit a specially crafted HTML page hosted by an attacker. Once loaded, the malicious script interacts with the PictureInPicture API in a manner that triggers the premature deallocation of critical memory blocks associated with window management or video rendering processes. By carefully crafting heap allocations and frees, an attacker can overwrite freed memory with controlled data structures, effectively gaining control over program execution flow. This manipulation allows for arbitrary code execution outside the restrictive Chrome sandbox environment, which is designed to isolate web content from the underlying operating system. The severity of this issue is classified as High by the Chromium security team due to its potential to bypass significant security boundaries and execute native code on the victim's machine.
The operational impact of successfully exploiting this vulnerability extends far beyond simple data theft or session hijacking. An attacker who achieves arbitrary code execution within the context of a browser process can potentially escape the sandbox isolation, thereby gaining access to sensitive files, system configurations, and other applications running on the host operating system. This level of compromise effectively neutralizes one of the primary defenses against web-based attacks, as the malicious payload operates with the same privileges as the user account under which Chrome is executing. Furthermore, because the attack vector involves a crafted HTML page, it can be delivered through various means such as phishing emails, compromised websites, or drive-by downloads, making it a versatile tool for advanced persistent threats and targeted espionage campaigns. The reliance on social engineering underscores the importance of user awareness alongside technical mitigations, although the severity of the underlying flaw makes even cautious users vulnerable if they inadvertently interact with malicious media elements.
To mitigate this risk, organizations and individual users must ensure that Google Chrome is updated to version 157.0.8103.38 or later as soon as possible. These updates contain patches that correct the memory management logic within the PictureInPicture module, ensuring that objects are properly retained until they are no longer needed by the application. In environments where immediate patching may not be feasible due to operational constraints, implementing strict content security policies and restricting the execution of untrusted scripts can help reduce the attack surface. Additionally, deploying endpoint detection and response solutions capable of monitoring for anomalous memory access patterns or unauthorized process creation can provide an additional layer of defense against exploitation attempts. It is also advisable to disable unnecessary browser features such as picture-in-picture if they are not required by end users, thereby eliminating the specific code path vulnerable to this flaw. Continuous monitoring and adherence to industry standards like MITRE ATT&CK technique T1059 for command and script interpretation can aid in detecting post-exploitation activities that may result from successful exploitation of such vulnerabilities.