CVE-2026-79021 in Chrome
Summary
by MITRE • 08/26/2026
Missing authorization in InterestGroups in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process to bypass system access restrictions via a crafted PDF file. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as missing authorization within InterestGroups in Google Chrome prior to version 152.0.7977.65 represents a critical failure in the browser's process isolation and access control mechanisms. This flaw specifically affects the implementation of Privacy Sandbox features, which are designed to enable targeted advertising while preserving user privacy by grouping users into cohorts rather than tracking individuals. InterestGroups serve as the underlying data structure for these cohorts, storing information about ads that have been shown to a user based on their browsing history and interactions. The security severity is classified as Low within the Chromium ecosystem because the exploitation requires an initial foothold in a lower-privilege context, yet it remains significant due to its potential to escalate privileges from a sandboxed environment to access sensitive system resources or browser internals that should remain inaccessible.
The technical root cause of this vulnerability lies in insufficient validation checks when handling InterestGroup data structures within the renderer process. In Chrome's multi-process architecture, each tab and extension runs in a separate renderer process with restricted permissions to prevent malicious code from affecting other parts of the system or the operating system itself. However, when processing crafted PDF files, the browser failed to properly verify whether the requesting entity had the necessary authorization to access specific InterestGroup data. This oversight allowed an attacker who had already compromised the renderer process through a separate vulnerability or exploit chain to bypass these restrictions. By crafting a malicious PDF file that triggers specific code paths within the browser's rendering engine, an attacker could manipulate how InterestGroups are accessed and modified, effectively circumventing the intended security boundaries imposed by the sandbox.
The operational impact of this flaw is primarily centered on privilege escalation from a low-privilege renderer process to gain unauthorized access to higher-level browser data or system resources. While the initial compromise might be limited to reading certain cookies or local storage within that specific tab, the ability to bypass InterestGroup authorization checks can lead to broader information disclosure. An attacker could potentially extract sensitive user profiling data intended for advertising purposes, which may include detailed behavioral histories and inferred interests. Furthermore, depending on how these groups are integrated with other browser features, there is a risk of cross-site scripting or state manipulation that could affect the integrity of the browsing session. Although it does not directly allow arbitrary code execution in the context of the user's account without further exploitation steps, it weakens the overall security posture by eroding trust in the sandbox model and potentially exposing private data to malicious actors who have achieved renderer compromise through other vectors such as drive-by downloads or phishing campaigns involving PDF documents.
To mitigate this risk, users are strongly advised to update Google Chrome immediately to version 152.0.7977.65 or later, where the authorization checks for InterestGroups have been hardened and validated against unauthorized access attempts. For organizations deploying Chrome via enterprise policies, ensuring automatic updates are enabled is crucial to maintain protection against such vulnerabilities as they are discovered. Additionally, security teams should monitor for indicators of compromise related to renderer process anomalies and enforce strict content security policies that limit the execution of untrusted scripts within PDF viewers or embedded browsers. From a defensive perspective, this vulnerability aligns with CWE-269 Improper Privilege Management and is relevant to ATT&CK technique T1055 Process Injection if an attacker attempts to leverage the compromised renderer for further lateral movement. Continuous monitoring of browser update deployments and regular security assessments will help minimize exposure to such access control flaws in web browsing environments.