CVE-2026-121178 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Aura in Google Chrome prior to 157.0.8103.38 allowed a remote attacker who had compromised the renderer process to potentially 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 flaw within Google Chrome's Aura window manager component represents a critical memory safety issue that undermines the browser's core isolation mechanisms. This defect, present in versions prior to 157.0.8103.38, stems from improper management of object lifecycles during UI rendering operations. Specifically, the Aura subsystem failed to correctly invalidate or nullify pointers after freeing associated memory structures. When a crafted HTML page triggers specific layout or compositing actions, it can cause the renderer process to access memory that has already been deallocated and potentially reallocated for other purposes. This scenario creates an opportunity for heap corruption, where the attacker gains control over how freed memory is interpreted by subsequent operations within the browser's graphics stack.
From a technical perspective, this flaw falls under CWE-416, Use After Free, which describes situations where software continues to use a pointer after it has been freed. In the context of Chrome’s architecture, Aura serves as the window manager for Chromium-based applications on Linux and other platforms, handling input events, geometry management, and surface composition. The renderer process operates within a strict sandbox designed to prevent arbitrary code execution if compromised. However, because Aura often interacts with system-level graphics APIs and manages resources that may be shared or referenced across different security contexts, an attacker who has already achieved code execution within the renderer can exploit this dangling pointer to escape the sandbox boundary. By carefully crafting HTML content that manipulates DOM elements and triggers specific rendering paths, the attacker forces the browser to dereference a freed address in a controlled manner, allowing them to overwrite critical data structures or execute arbitrary instructions outside the restricted environment.
The operational impact of this vulnerability is severe due to its potential for sandbox escape. While initial exploitation requires compromising the renderer process, which typically involves exploiting another vulnerability such as an out-of-bounds read or write, the availability of a reliable use-after-free primitive in Aura significantly lowers the barrier for achieving full system compromise. Once arbitrary code execution occurs outside the sandbox, the attacker gains unrestricted access to the underlying operating system resources. This can lead to data exfiltration, installation of persistent malware, lateral movement within a network, or complete control over the victim's device. The severity is rated as High by Chromium security teams because it directly attacks the fundamental trust model that protects users from malicious web content.
This vulnerability aligns with MITRE ATT&CK technique T1203, Exploitation for Client Execution, and specifically relates to sandbox escape techniques often categorized under privilege escalation or container breakout depending on the deployment context. The attack vector is classified as Remote (ATT&CK T1190), meaning it can be triggered via a malicious website without any user interaction beyond visiting the page. Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where the memory management logic in Aura has been corrected to ensure pointers are properly invalidated upon deallocation. Additionally, enabling strict Content Security Policies and utilizing browser hardening features such as site isolation can reduce the likelihood of initial renderer compromise, thereby mitigating the risk chain that leads to this specific exploitation path. Organizations should prioritize patching endpoints running affected versions to close this critical security gap.