CVE-2026-121238 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Source in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free condition within the Source component of Google Chrome prior to version 157.0.8103.38 represents a critical memory safety flaw that undermines the browser's sandboxing mechanisms. This type of error occurs when a program continues to use a pointer after the memory it points to has been freed, leading to undefined behavior that can be exploited by malicious actors. In this specific instance, the flaw resides in how Chrome handles resources associated with web content sources, where an object is deallocated but remains accessible through lingering references within the browser's internal data structures.
The operational impact of this vulnerability is severe because it allows a remote attacker to execute arbitrary code inside the sandboxed environment. Typically, browsers employ sandboxes to restrict the privileges of processes that handle untrusted web content, thereby limiting the damage an exploit can cause. However, by leveraging the use-after-free condition in the Source component, an attacker crafted HTML page could manipulate memory states to bypass these restrictions. This effectively neutralizes a primary defense layer, enabling code execution with potentially elevated privileges relative to other sandboxed processes or allowing access to sensitive data that should remain isolated from web content.
From a technical classification perspective, this vulnerability aligns closely with CWE-416, which defines use after free as an error where the program uses memory after it has been freed. This category of bugs is particularly dangerous because they are often difficult to detect during standard testing and can lead to various forms of exploitation including arbitrary code execution, denial of service, or information disclosure depending on how the freed memory is reused. The ability to execute code within the sandbox highlights a failure in Chrome's object lifecycle management for source-related objects, indicating that reference counting or ownership semantics were not correctly maintained during resource deallocation.
In terms of threat modeling and attack vectors, this vulnerability maps to MITRE ATT&CK techniques related to initial access and defense evasion. Specifically, it relates to the exploitation of software vulnerabilities via web browsers (T1189) and potentially bypassing application sandbox restrictions if the exploit chain successfully escalates privileges or escapes the immediate process boundary. The use of a crafted HTML page indicates that this is a remote code execution vulnerability triggered by user interaction with maliciously designed web content, making it a significant risk for users browsing untrusted sites without additional protective measures like strict Content Security Policies or sandboxing extensions.
Mitigation strategies primarily involve updating to the patched version 157.0.8103.38 or later, which addresses the memory management logic in the Source component to ensure that pointers are properly nullified after deallocation and that references are invalidated correctly. For organizations unable to patch immediately, deploying browser hardening techniques such as disabling JavaScript execution for untrusted domains using enterprise policies can reduce the attack surface. Additionally, ensuring that users have up-to-date operating system-level protections enabled, including memory protection features like DEP and ASLR, provides an additional layer of defense against exploitation attempts derived from this vulnerability.