CVE-2026-121233 in Chrome
Summary
by MITRE • 11/03/2026
Type confusion in CacheStorage 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: High)
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified as a type confusion flaw within the CacheStorage component of Google Chrome prior to version 157.0.8103.38 represents a critical memory safety issue that undermines the browser's sandboxing mechanisms. Type confusion vulnerabilities occur when an application incorrectly interprets the data type of a variable or object in memory, leading to operations being performed on data structures with incompatible types. In this specific instance, the flaw resides within CacheStorage, a core API used by web applications to store and retrieve cached resources for improved performance and offline functionality. The presence of this defect allows an attacker who can trick a user into visiting a specially crafted HTML page to manipulate how Chrome handles memory allocations and references related to cache entries. By exploiting the misinterpretation of object types, the malicious code can bypass standard type checks that are designed to prevent out-of-bounds accesses or invalid pointer dereferences, thereby gaining unauthorized access to sensitive areas of browser memory.
From a technical perspective, this vulnerability falls under the category of CWE-843, which refers to Accessing Memory with Incorrect Type Specification. The exploitation vector relies on the attacker constructing an HTML page that triggers specific JavaScript operations within CacheStorage, causing the underlying C++ code in Chromium to treat one data structure as another. This discrepancy can lead to arbitrary read and write capabilities within the browser process memory space. Since Chrome employs a multi-process architecture with strict sandboxing to isolate web content from the operating system, such an exploit is particularly dangerous because it aims to escape this isolation. By achieving arbitrary code execution inside the sandboxed renderer or utility processes, the attacker can potentially break out of the sandbox entirely, depending on the specific privileges granted to the compromised process and the effectiveness of other mitigations like Control Flow Integrity (CFI) or hardware-based protections such as DEP and ASLR.
The operational impact of this vulnerability is severe, classified with a High security severity by the Chromium project due to its potential for remote code execution without user interaction beyond visiting a malicious site. An attacker could use this flaw to install malware, steal sensitive data such as cookies and session tokens, or establish persistent access to the victim's system. The ability to execute arbitrary code inside the sandbox significantly elevates the risk profile because it compromises the fundamental security model of modern web browsers. This type of exploit is often utilized in drive-by download attacks where no additional software installation by the user is required. Furthermore, if the vulnerability allows for information disclosure prior to full exploitation, it could facilitate further reconnaissance and privilege escalation steps within the compromised environment.
In terms of threat intelligence frameworks, this incident aligns with MITRE ATT&CK techniques related to Initial Access via Spearphishing Link or Drive-by Compromise, specifically leveraging software vulnerabilities in web browsers. The exploit chain likely involves crafting a malicious webpage that triggers the type confusion during cache operations, followed by heap spraying or other memory corruption techniques to achieve code execution. Defense-in-depth strategies are essential for mitigating such risks. Users and organizations should ensure that Google Chrome is updated to version 157.0.8103.38 or later immediately upon availability. Additionally, enabling automatic updates can help prevent exposure to known vulnerabilities in the future. Security teams should also monitor browser telemetry and endpoint detection systems for anomalies indicative of memory corruption exploits, such as unusual heap activity or attempts to access restricted memory regions. While sandboxing provides a robust layer of defense, it is not impenetrable against sophisticated type confusion bugs that target core components like CacheStorage, making timely patch management the most effective countermeasure.