CVE-2026-118339 in Chrome
Summary
by MITRE • 10/28/2026
Use after free in Animation in Google Chrome prior to 156.0.8078.73 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified as a use-after-free condition within the Animation component of Google Chrome prior to version 156.0.8078.73 represents a critical memory management error that compromises the integrity and confidentiality of user data. This flaw arises when the browser's rendering engine fails to properly manage the lifecycle of animation objects, specifically allowing access to memory regions after they have been deallocated by the system. In modern web browsers like Chrome, complex animations are often handled through JavaScript APIs or CSS transitions that interact with underlying C++ components responsible for compositing and layout updates. When an attacker crafts a malicious HTML page containing specially designed scripts or stylesheets, they can trigger specific sequences of events that cause these animation objects to be freed while still being referenced by other active processes within the browser's rendering pipeline. This discrepancy between object reference counts and actual memory deallocation creates a window where stale pointers remain valid in certain contexts but point to uninitialized or recycled memory locations.
From a technical perspective, this use-after-free vulnerability exploits the gap between high-level web standards implementation and low-level memory safety guarantees inherent in C++ based browsers. The Chromium engine relies heavily on smart pointers and reference counting mechanisms to prevent such errors, yet complex interactions involving asynchronous animation frames can sometimes bypass these safeguards if not carefully synchronized. An attacker leveraging this flaw can manipulate the heap layout by allocating specific data structures immediately after the freed animation object's memory is reclaimed. By controlling the content of this newly allocated memory, which might include function pointers or vtable entries in C++ objects, the attacker gains the ability to redirect execution flow during subsequent operations on the stale pointer. This mechanism effectively transforms a simple memory corruption bug into a powerful code execution primitive that operates within the browser's sandboxed environment.
The operational impact of this vulnerability is severe due to its potential for remote code execution via a crafted HTML page, which aligns with common attack vectors observed in web-based exploits. Since Chrome employs a multi-process architecture where renderer processes are isolated from the operating system kernel and other sensitive components through sandboxes, successful exploitation requires breaking out of this sandbox boundary. However, use-after-free vulnerabilities provide attackers with precise control over memory contents, facilitating arbitrary read-write primitives that can be chained to bypass security mitigations such as Control Flow Integrity (CFI) or Data Execution Prevention (DEP). Once the attacker achieves code execution within the renderer process, they may attempt further exploitation techniques to escape the sandbox and gain access to the host system. This could lead to full compromise of the user's machine, including theft of sensitive credentials, installation of persistent malware, or use as part of a botnet infrastructure.
This incident is categorized under CWE-416: Use After Free in the Common Weakness Enumeration framework, which highlights the danger of accessing memory after it has been freed without proper validation. In terms of adversary tactics and techniques, this vulnerability aligns with ATT&CK technique T1203: Exploitation for Client Execution, where attackers deliver malicious content through web pages to trigger local software vulnerabilities. The high severity rating assigned by Chromium security reflects the ease with which such bugs can be weaponized given their prevalence in complex rendering engines and the significant impact on user safety. Mitigation strategies primarily involve updating Google Chrome to version 156.0.8078.73 or later, where developers have implemented stricter checks during animation object lifecycle management and enhanced memory sanitization routines. Additionally, users should enable automatic updates for their browsers to ensure timely patching of such critical vulnerabilities as they are discovered by the security community.