CVE-2026-19153 in Chrome
Summary
by MITRE • 08/07/2026
Insufficient validation of untrusted input in Workers in Google Chrome prior to 151.0.7922.109 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 08/07/2026
This vulnerability represents a critical security flaw in Google Chrome's worker process implementation that existed prior to version 151.0.7922.109. The issue stems from inadequate input validation mechanisms within the worker execution environment, creating a pathway for privilege escalation attacks. When an attacker successfully compromises the renderer process, they can exploit this weakness to bypass site isolation protections that are fundamental to Chrome's security architecture. Site isolation serves as a critical defense mechanism that prevents malicious websites from accessing data from other origins by maintaining separate processes for each site. The vulnerability manifests when untrusted HTML content is processed through worker threads without proper sanitization of input parameters, allowing crafted payloads to manipulate the execution flow.
The technical nature of this flaw aligns with CWE-20, which describes improper input validation issues in software systems. This weakness specifically affects the worker thread implementation where JavaScript code executes in background processes separate from the main UI thread but still within the same security boundary. The vulnerability operates at the intersection of process isolation and cross-origin resource management, where the lack of proper input sanitization creates a vector for attackers to escape containment boundaries. Attackers can leverage this by constructing malicious HTML pages that contain specially crafted worker instructions designed to bypass the normal security constraints imposed by site isolation.
The operational impact of this vulnerability is significant as it undermines one of Chrome's core security models designed to protect users from cross-site scripting attacks and data leakage between different origins. When successfully exploited, the vulnerability allows an attacker with renderer process access to execute arbitrary code in contexts where they should be restricted, potentially enabling full system compromise or data exfiltration. The attack requires initial compromise of the renderer process through techniques such as exploiting other vulnerabilities in Chrome's UI rendering components or social engineering attacks that lead users to visit malicious sites. Once inside the renderer process, the attacker can craft HTML pages that trigger the worker bypass mechanism, effectively neutralizing site isolation protections and establishing a foothold for further exploitation.
This vulnerability directly relates to ATT&CK technique T1059.007 which covers JavaScript and VBScript execution within browser environments. The security implications extend beyond simple privilege escalation to encompass complete breakdown of Chrome's multi-process architecture that is designed to contain malicious code execution. Organizations should implement immediate patching strategies targeting Chrome versions 151.0.7922.109 and later, as well as consider network-level monitoring for suspicious HTML content patterns that might indicate exploitation attempts. System administrators should also review browser security policies and ensure that automatic updates are enabled to maintain protection against similar vulnerabilities. The incident highlights the importance of maintaining strict input validation across all execution contexts within modern web browsers where multiple security layers must work in concert to prevent exploitation.
The remediation strategy involves updating Chrome installations to versions that include proper input validation mechanisms for worker threads, ensuring that untrusted HTML content undergoes comprehensive sanitization before being processed by background worker processes. Security teams should also implement monitoring solutions that can detect anomalous behavior patterns associated with worker process execution and cross-origin access attempts. Organizations may need to consider additional browser hardening measures such as disabling unnecessary worker APIs or implementing strict Content Security Policy directives that limit the scope of worker thread capabilities in enterprise environments. The vulnerability underscores the critical importance of maintaining robust security boundaries even within complex multi-process architectures where traditional containment mechanisms can be bypassed through sophisticated exploitation techniques.