CVE-2026-78985 in Chrome
Summary
by MITRE • 08/26/2026
Incorrect reference resolution in FileSystem in Google Chrome prior to 152.0.7977.65 allowed a remote attacker leveraging social engineering to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as an incorrect reference resolution within the FileSystem API of Google Chrome prior to version 152.0.7977.65 represents a significant breach in browser isolation mechanisms. This flaw stems from improper handling of file path references, which allows for directory traversal or ambiguous resource resolution when processing user-supplied input. In modern web browsers, the File System Access API and related interfaces are designed to provide controlled access to local files while maintaining strict sandbox boundaries that prevent web content from interacting with arbitrary system resources without explicit user permission. However, in this specific instance, the logic governing how these references were resolved contained a defect that permitted an attacker to manipulate path strings in ways that bypassed expected validation checks. This type of error is commonly categorized under CWE-20 Improper Input Validation and specifically relates to CWE-22 Path Traversal: '..' Sequences, where insufficient sanitization allows access to files or directories outside the intended scope.
The operational impact of this vulnerability is severe due to its potential for arbitrary code execution outside the browser's sandbox environment. By crafting a malicious HTML page that exploits the reference resolution flaw, an attacker can trick a user into interacting with specific file paths or triggering actions that lead to unauthorized access to sensitive system files. Once such access is achieved through social engineering tactics, which are often required to gain initial trust and trigger the necessary browser permissions, the attacker gains the ability to execute arbitrary code on the victim's machine. This effectively breaks out of the restrictive sandbox context where Chrome typically confines web content, thereby granting the adversary elevated privileges comparable to those of a local user account. The severity is rated as Medium by Chromium security standards because while it requires social engineering and specific browser versions, the resulting impact includes full system compromise rather than mere data exfiltration or denial of service.
From an offensive security perspective, this vulnerability aligns with several techniques in the MITRE ATT&CK framework. It relates to T1059 Command and Scripting Interpreter, as it facilitates the execution of code on the target system. Furthermore, it connects to T1204 User Execution, highlighting the reliance on social engineering to induce user interaction. The exploitation path also touches upon T1083 File and Directory Discovery if the attacker uses the traversal capability to map out sensitive directories before deploying payloads. Understanding these mappings helps security teams prioritize remediation efforts based on how this flaw fits into broader attack chains observed in real-world campaigns targeting browser-based entry points.
Mitigation for this vulnerability primarily involves updating Google Chrome to version 152.0.7977.65 or later, where the reference resolution logic has been corrected to properly validate and sanitize file paths before processing them. Organizations should enforce automatic update policies to ensure all endpoints are running patched versions of the browser. Additionally, security awareness training is crucial to mitigate the social engineering aspect of this exploit, as users must be educated on recognizing suspicious prompts requesting file system access or unusual behavior from web pages. Implementing strict Content Security Policies and disabling unnecessary APIs can further reduce the attack surface by limiting the capabilities available to untrusted scripts. Regular auditing of browser configurations and monitoring for anomalous process executions originating from Chrome processes can also aid in detecting potential exploitation attempts before they result in full compromise.