CVE-2026-106403 in Chrome
Summary
by MITRE • 10/07/2026
Incorrect authorization in Accessibility in Google Chrome prior to 155.0.8059.39 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified as an incorrect authorization issue within the Accessibility subsystem of Google Chrome prior to version 155.0.8059.39 represents a significant breach in the browser's multi-process architecture integrity. This flaw specifically impacts the mechanism that enforces site isolation, a critical security feature designed to prevent cross-site scripting and data leakage by ensuring that resources from different origins are kept strictly separate within distinct renderer processes. The root cause lies in an authorization logic error where the accessibility service fails to properly validate whether a requesting process has legitimate permission to access sensitive interface elements or state information associated with other sites. This misconfiguration allows a compromised renderer process, which might have been exploited through a remote attack vector such as a crafted HTML page containing malicious scripts, to bypass these isolation boundaries.
From an operational perspective, the ability of a renderer process to circumvent site isolation fundamentally undermines the browser's defense-in-depth strategy. Site isolation is intended to limit the blast radius of any single compromise; if one tab or frame is exploited, the attacker should not be able to access data from other tabs or frames belonging to different origins. By exploiting this authorization flaw, an attacker can potentially read sensitive information such as cookies, local storage contents, or DOM elements from sites that are supposed to be isolated from the compromised context. This effectively transforms a contained renderer compromise into a broader cross-site scripting scenario, enabling the exfiltration of user credentials, session tokens, and other personally identifiable information without triggering standard same-origin policy warnings.
This vulnerability aligns with CWE-269, which describes Improper Control of Interaction With Untrusted Input in contexts where authorization checks are bypassed due to flawed logic rather than missing controls. Furthermore, the exploitation technique maps directly to MITRE ATT&CK techniques related to Process Injection and Defense Evasion, specifically leveraging legitimate system components like accessibility APIs to maintain persistence or escalate privileges within the browser environment. The use of a crafted HTML page indicates that this is a remote code execution vector requiring user interaction, such as visiting a malicious website, which classifies it under initial access vectors but with elevated impact due to the isolation bypass capability.
Mitigation for this vulnerability requires immediate updates to Google Chrome and its underlying Chromium engine to version 155.0.8059.39 or later, where the authorization checks within the accessibility subsystem have been corrected to strictly enforce origin boundaries. For organizations managing large fleets of endpoints, deploying automated patch management solutions is essential to ensure timely remediation across all user devices. Additionally, security teams should monitor for indicators of compromise that suggest attempts to exploit renderer process isolation failures, such as unusual access patterns by browser helper objects or accessibility services interacting with unexpected origins. While no known workarounds exist other than updating the software, enforcing strict content security policies and disabling unnecessary extensions can reduce the attack surface available to initial exploitation vectors before patches are applied.