CVE-2026-121167 in Chrome
Summary
by MITRE • 11/03/2026
Incorrect authorization in Permissions in Google Chrome prior to 157.0.8103.38 allowed a remote attacker who had compromised the renderer process to bypass system access restrictions via a crafted HTML page. (Chromium security severity: Medium)
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified as an incorrect authorization issue within Google Chrome prior to version 157.0.8103.38 represents a critical failure in the browser's permission management subsystem, specifically affecting how access rights are validated for system-level resources. This flaw resides deep within the Chromium architecture, where the separation of privileges between different processes is paramount for maintaining security boundaries. The renderer process, which handles the execution of web content such as JavaScript and HTML, operates under strict sandboxing to limit its ability to interact with the host operating system or sensitive user data. However, due to this authorization error, a remote attacker who has successfully compromised the renderer process through other means can exploit this weakness to bypass these established access restrictions. The attack vector involves crafting a specific HTML page that triggers the flawed permission check, allowing the malicious code within the sandboxed environment to escalate its privileges and perform actions outside its intended scope.
From a technical perspective, this vulnerability highlights a breakdown in the principle of least privilege enforced by Chrome's multi-process architecture. When a renderer process is compromised, typically via a cross-site scripting attack or exploitation of another rendering engine bug, it should remain isolated from sensitive system functions. The incorrect authorization logic fails to properly validate whether the requesting entity has the necessary permissions before granting access to restricted APIs or resources. This allows the attacker to manipulate internal state variables or bypass security checks that are supposed to prevent unauthorized interaction with browser features like clipboard access, file system operations, or network requests that might leak sensitive information. The severity is classified as medium by Chromium because while it requires an initial compromise of the renderer process, the subsequent privilege escalation can lead to significant data exfiltration or further lateral movement within the user's environment if not contained properly.
The operational impact of this vulnerability is substantial for users relying on Chrome for secure browsing activities. An attacker leveraging this flaw could potentially access sensitive information stored in browser memory, such as cookies, session tokens, or autofilled personal details, which are typically protected from renderer-level access. Furthermore, the ability to bypass system access restrictions means that malicious scripts could interact with hardware interfaces or operating system services without user consent, leading to potential data theft, surveillance, or installation of additional malware payloads. This undermines the trust model of web browsers where users expect their browsing activity and personal data to be isolated from untrusted third-party content. The risk is particularly acute in enterprise environments or for high-value targets where even a medium-severity vulnerability can serve as a stepping stone for more sophisticated attacks like drive-by downloads or persistent backdoors.
Mitigation strategies primarily involve updating the browser software immediately, as Google has released patches in version 157.0.8103.38 and later that correct the authorization logic within the permission handling subsystem. Administrators should ensure automatic updates are enabled to prevent exposure during the window between vulnerability disclosure and patch deployment. Additionally, users can employ security extensions or browser configurations that restrict permissions for untrusted sites, adding an extra layer of defense against renderer-based attacks. From a defensive engineering standpoint, this incident underscores the importance of rigorous code review processes focused on privilege boundaries and the implementation of strict origin checks in all permission-granting APIs. Security teams should also monitor for indicators of compromise related to renderer process anomalies or unexpected system calls originating from browser contexts, as these may signal active exploitation attempts targeting similar architectural weaknesses.
This vulnerability aligns with CWE-269, which describes Improper Privilege Management, where a software application does not properly assign privileges to actors based on their authorization levels. It also maps to the MITRE ATT&CK framework under techniques related to privilege escalation and defense evasion, specifically how attackers leverage existing access within a sandboxed environment to break out into more privileged contexts. Understanding these mappings helps security professionals categorize similar flaws across different software ecosystems and prioritize remediation efforts based on the potential for lateral movement and data loss. Continuous monitoring of browser update cycles and adherence to recommended configuration baselines remain essential defenses against such architectural exploits in modern web browsers.