CVE-2026-121091 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 obtain sensitive information via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an incorrect authorization issue within the permissions system of Google Chrome prior to version 157.0.8103.38 represents a significant breach in the browser's isolation model, specifically targeting the boundary between renderer processes and sensitive user data or application states. This flaw allows a remote attacker who has already achieved code execution within a compromised renderer process to escalate privileges by bypassing intended access controls. The core technical failure lies in the improper validation of permissions when requests are made from untrusted contexts, such as those originating from maliciously crafted HTML pages hosted on external domains or injected via cross-site scripting vectors that have managed to execute scripts within the sandboxed environment.
From a technical perspective, modern browsers like Chrome rely heavily on process isolation and strict origin policies to prevent one tab or frame from accessing data belonging to another. The renderer processes are designed to be untrusted environments where web content executes with limited privileges. However, this vulnerability indicates that certain permission checks were either missing, incorrectly implemented, or susceptible to race conditions during the handling of specific API calls or resource requests. By crafting a specialized HTML page containing malicious JavaScript, an attacker can exploit these gaps in authorization logic to request access to sensitive information that should remain restricted to privileged contexts or other origins. This effectively undermines the sandboxing mechanism intended to contain potential exploits within the renderer process.
The operational impact of this vulnerability is substantial for users who visit compromised websites or are targeted by drive-by download attacks. An attacker leveraging this flaw can exfiltrate sensitive data such as cookies, local storage contents, session tokens, or other user-specific information that resides in memory accessible to the browser's permission system but not intended for public web pages. This leads directly to privacy violations and potential account compromise if authentication credentials are stolen. Furthermore, because the attack vector is remote and requires no physical access or prior installation of malware on the victim’s machine beyond visiting a webpage, it poses a high risk in phishing campaigns and malicious ad networks that distribute such crafted content widely across the web ecosystem.
In terms of industry standards classification, this vulnerability aligns with CWE-269, which denotes Improper Privilege Management, as well as CWE-862, Missing Authorization, reflecting the failure to enforce proper access control policies. Within the MITRE ATT&CK framework for enterprise security, this behavior corresponds to techniques involving T1059 Command and Scripting Interpreter through JavaScript execution within a browser context, followed by T1005 Data from Local System where sensitive data is collected via unauthorized API calls. The severity rating of Medium in Chromium reflects that while the vulnerability allows significant information disclosure, it requires an initial compromise of the renderer process, which typically necessitates successful exploitation of another flaw or social engineering to gain entry into that isolated environment.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these authorization checks have been corrected and hardened against such bypass attempts. For organizations managing large fleets of endpoints, ensuring automatic update policies are enforced is critical to closing this window of exposure. Additionally, users should employ browser extensions that enforce strict content security policies and block unauthorized cross-origin requests where possible, although the most effective defense remains keeping the browser software current with the latest security patches released by Google. Security teams should also monitor for indicators of compromise related to unusual network traffic patterns originating from browser processes accessing external domains unexpectedly, which may signal active exploitation attempts against unpatched systems.