CVE-2026-87491 in Chrome
Summary
by MITRE • 09/09/2026
Out of bounds write in V8 in Google Chrome prior to 153.0.8010.36 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 • 09/09/2026
The vulnerability identified as an out-of-bounds write within the V8 JavaScript engine represents a critical memory safety flaw that undermines the integrity of Google Chrome prior to version 153.0.8010.36. This specific defect allows for arbitrary code execution by exploiting improper bounds checking during array or buffer manipulation operations handled by the JIT compiler and runtime environment. When an attacker crafts a malicious HTML page containing specially constructed JavaScript, they can trigger conditions where memory writes exceed the allocated boundaries of internal data structures. This overflow condition enables the overwriting of adjacent memory regions, which is particularly dangerous in the context of browser security models because it facilitates escape from the renderer process sandbox to achieve arbitrary code execution on the host system.
From a technical perspective, this flaw aligns with CWE-787: Out-of-bounds Write, as it involves writing data beyond the intended buffer limits due to insufficient validation of input indices or sizes within the V8 engine's internal logic. The exploitation chain typically begins with user interaction via a phishing vector or compromised website that hosts the malicious HTML payload. Once executed by the browser, the crafted script manipulates heap memory structures in ways that corrupt metadata or overwrite function pointers and object headers. This corruption allows the attacker to control program flow, effectively bypassing modern mitigation techniques such as DEP and ASLR if combined with additional exploitation primitives like information leaks. The severity is classified as medium within the Chromium security framework because while it requires user interaction and specific conditions to exploit successfully, its impact on system compromise is severe when realized.
The operational impact of this vulnerability extends beyond simple data corruption or denial of service. Successful exploitation grants a remote attacker full control over the browser process context, which can be leveraged to install malware, steal sensitive credentials stored in the browser, conduct session hijacking attacks, or pivot into internal network resources depending on the user's privileges and browsing habits. Since V8 is deeply integrated into Chrome’s rendering pipeline, any flaw here affects all users of affected versions regardless of their specific configuration settings, making widespread exposure likely until patches are applied. The ability to execute arbitrary code inside the sandbox signifies a failure in the isolation boundaries that protect the operating system from untrusted web content, thereby elevating the risk profile significantly for enterprise and individual deployments alike.
Mitigation strategies primarily involve immediate patching of all affected Chrome installations to version 153.0.8010.36 or later where these bounds checking mechanisms have been hardened by Google’s security team. Organizations should enforce automated update policies to ensure rapid deployment of fixes across endpoints. Additionally, users can reduce exposure risk by employing browser hardening techniques such as disabling JavaScript on untrusted sites using extensions like NoScript or configuring strict content security policies if running custom web applications. Monitoring for anomalous network activity originating from the Chrome process and utilizing endpoint detection and response solutions that monitor memory access patterns can also help detect attempted exploitation in real-time before full compromise occurs, aligning with ATT&CK techniques related to initial access via spearphishing links and defense evasion through sandbox escape methods.