CVE-2026-78999 in Chrome
Summary
by MITRE • 08/26/2026
Improper privilege management in Navigation in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process and leveraged social engineering to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified in Google Chrome prior to version 152.0.7977.65 represents a critical failure in privilege management within the browser's navigation subsystem, specifically classified under CWE-269 Improper Privilege Management. This flaw allows an attacker who has already achieved partial compromise of the renderer process to escalate privileges and escape the security sandbox that isolates web content from the underlying operating system. The severity is rated as medium by Chromium security standards because it requires a specific combination of conditions, yet its impact remains significant due to the potential for arbitrary code execution outside the protected environment.
The technical mechanism behind this vulnerability centers on how Chrome handles navigation events and permission checks during page transitions or frame loads. When a renderer process initiates navigation, particularly through crafted HTML pages involving complex scripts or embedded objects, the browser's main thread must validate whether the requesting context has sufficient privileges to perform certain actions that might affect higher-privileged processes. In this instance, the validation logic failed to properly restrict access based on the current security origin and sandbox level. This oversight permitted a malicious actor leveraging social engineering techniques to trick a user into visiting a specially crafted webpage containing exploit code designed to trigger the flawed navigation path.
The operational impact of this vulnerability is severe because it facilitates a browser escape, moving from a low-privilege renderer context to a higher-privilege state outside the sandbox. Once an attacker executes arbitrary code outside the sandbox, they gain direct access to system resources that are normally protected by Chrome's multi-process architecture and site isolation policies. This can lead to full system compromise, including data exfiltration, installation of persistent malware, or further lateral movement within a network if the user is part of a larger infrastructure. The reliance on social engineering indicates that this vulnerability is often exploited in targeted attacks where human interaction is required to initiate the malicious payload, making it particularly dangerous in phishing campaigns aimed at high-value targets.
From an industry standard perspective, this flaw aligns with ATT&CK technique T1059 Command and Scripting Interpreter, as the attacker uses crafted HTML and scripts to execute code. It also relates to T1210 Exploitation of Remote Services if viewed through the lens of web service exploitation, although it is more accurately described by privilege escalation vectors within a local application context. The failure to enforce proper access controls during navigation highlights gaps in implementing least-privilege principles for browser components that handle user-initiated actions with potential side effects on system state.
Mitigation strategies primarily involve updating Google Chrome to version 152.0.7977.65 or later, where the privilege management logic has been corrected to ensure strict validation of navigation requests against sandbox boundaries. Organizations should enforce automatic update policies for all endpoints running this browser to minimize exposure windows. Additionally, security awareness training is crucial to mitigate the social engineering aspect, as users must be educated to recognize and avoid suspicious links that may attempt to exploit such vulnerabilities through crafted web content. Implementing strict Content Security Policies (CSP) can also help restrict the execution of unauthorized scripts, although this does not fully replace the need for patching the underlying browser vulnerability.