CVE-2026-87658 in Chrome
Summary
by MITRE • 09/09/2026
Information leak in Extensions in Google Chrome prior to 153.0.8010.36 allowed a remote attacker leveraging social engineering to obtain cross-origin data via a crafted Chrome extension. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an information leak within the extensions subsystem of Google Chrome prior to version 153.0.8010.36 represents a significant breach in web isolation principles, specifically targeting the boundary between cross-origin contexts. This flaw allows a remote attacker who has successfully leveraged social engineering techniques to install or manipulate a malicious Chrome extension to access sensitive data belonging to other origins that are normally isolated from one another. The core technical issue stems from improper handling of permissions and context separation within the browser's extension architecture, which inadvertently exposes cross-origin resources such as cookies, local storage, or DOM content intended for different websites. By crafting an extension that exploits these misconfigurations, an attacker can bypass same-origin policy restrictions, effectively reading data across domain boundaries without user interaction beyond the initial installation phase.
From a technical perspective, this vulnerability aligns with CWE-200, which categorizes information exposure vulnerabilities where sensitive system or application information is disclosed to unauthorized actors. The exploitation vector relies heavily on social engineering, indicating that while the code flaw itself may be subtle, its activation requires user trust manipulation. This scenario maps directly to MITRE ATT&CK technique T1568.002, Software Deployment: Install Utility Script, as attackers often use malicious extensions disguised as legitimate tools or utilities to gain a foothold within the browser environment. Once installed, these extensions operate with elevated privileges compared to standard web pages, allowing them to access APIs and data stores that are typically restricted by default security policies. The medium severity rating assigned by Chromium reflects the balance between the ease of exploitation via social engineering and the potential impact on user privacy and data integrity.
The operational impact of this vulnerability is profound for end-users who rely on browser extensions for productivity, security, or utility functions. An attacker successfully exploiting this flaw could harvest session tokens, authentication cookies, personal identifiable information stored in local storage, or other sensitive cross-origin data that users assume are secure within their respective web applications. This compromise undermines the fundamental trust model of modern browsers, where different websites are expected to remain isolated from each other to prevent unauthorized data access. The consequences can range from account takeover and identity theft to broader surveillance if multiple extensions with overlapping permissions are abused in tandem. Users may find that their browsing history, form inputs, or private communications have been exfiltrated without any visible indication of the breach occurring within the browser interface.
Mitigation strategies must focus on both immediate remediation and long-term security hygiene. The primary defense is to update Google Chrome to version 153.0.8010.36 or later, where these permission handling flaws have been patched by the Chromium team. Administrators should enforce strict extension policies through group policy settings in enterprise environments to prevent the installation of unverified or unauthorized extensions. Users must adopt a cautious approach when installing browser add-ons, verifying the publisher's reputation and reviewing requested permissions before granting access. Regular audits of installed extensions can help identify any suspicious tools that may have been introduced via social engineering tactics. Additionally, enabling built-in security features such as Safe Browsing and keeping operating systems updated provides an additional layer of defense against malicious software delivery mechanisms often associated with this type of attack vector.