CVE-2026-121064 in Chrome
Summary
by MITRE • 11/03/2026
Improper input validation in Performance in Google Chrome prior to 157.0.8103.38 allowed a local attacker to potentially execute arbitrary code inside the sandbox via a local program. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an improper input validation flaw within the Performance component of Google Chrome prior to version 157.0.8103.38 represents a significant deviation from expected secure coding practices regarding data handling and boundary checks. This specific defect allows for the potential execution of arbitrary code inside the browser's sandbox environment, which is typically designed to isolate untrusted content from sensitive system resources. The root cause lies in the failure of the Performance module to adequately sanitize or validate inputs received during performance monitoring operations, such as those related to resource timing and navigation metrics. When a local program interacts with these internal APIs without proper constraints, it can exploit this lack of validation to inject malicious payloads that bypass standard security controls.
From a technical perspective, this flaw is categorized under CWE-20: Improper Input Validation, which encompasses any situation where software receives input data but fails to verify its integrity or format before processing. In the context of Chrome's architecture, performance metrics are often collected and processed in real-time to provide developers with insights into page load times and resource usage. If an attacker can manipulate these inputs through a local program, they may trigger buffer overflows, type confusion errors, or logic flaws that lead to memory corruption. This corruption can then be leveraged to achieve arbitrary code execution within the sandboxed renderer process, effectively breaking out of the intended isolation boundaries that protect the user's system from malicious web content.
The operational impact of this vulnerability is particularly concerning due to its local attack vector. While many browser vulnerabilities require a remote victim to visit a compromised website, this flaw can be triggered by any program running on the same machine as the browser instance. This significantly lowers the barrier for exploitation, allowing malware or insider threats with minimal privileges to escalate their access. By executing code inside the sandbox, an attacker gains the ability to read sensitive data stored within the browser profile, such as cookies, saved passwords, and browsing history. Furthermore, if additional vulnerabilities are chained together, this initial foothold could potentially lead to a full system compromise, although the primary risk remains the breach of confidentiality and integrity for user-specific browser data.
Industry standards classify this type of vulnerability under ATT&CK technique T1059: Command and Scripting Interpreter, as it involves executing code through local programs that interact with application internals. Additionally, it aligns with CWE-787: Out-of-bounds Write if the input validation failure results in memory corruption leading to arbitrary write operations. The Chromium security severity is rated as Low, likely because the sandbox provides a robust layer of defense against immediate system-wide compromise, but this rating should not be misinterpreted as indicating low risk for data privacy and integrity.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these input validation checks have been strengthened. For organizations managing large deployments of browsers, implementing automated patch management systems is essential to ensure timely application of security updates. Additionally, users should exercise caution when installing third-party applications that interact with browser processes and consider using application whitelisting solutions to restrict which programs can access sensitive system APIs. Regularly auditing local software for known vulnerabilities and maintaining strict privilege separation between user accounts and administrative tasks further reduces the attack surface available to potential exploiters targeting this specific input validation flaw.