CVE-2026-121059 in Chrome
Summary
by MITRE • 11/03/2026
Information leak in Core in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to leak cross-origin data via a crafted HTML page. (Chromium security severity: Medium)
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an information leak within the core components of Google Chrome, specifically affecting versions prior to 157.0.8103.38, represents a significant breach in browser isolation mechanisms. This flaw allows a remote attacker to exfiltrate sensitive cross-origin data by leveraging a crafted HTML page. The severity is classified as Medium according to Chromium security standards, indicating that while the exploit requires user interaction or specific conditions to trigger successfully, the potential for unauthorized access to private information remains substantial. Such vulnerabilities typically arise from failures in enforcing strict origin policies, which are fundamental to web security and prevent scripts running on one site from accessing data associated with another unrelated site.
At a technical level, this issue likely stems from an improper handling of memory or state management within the browser's core rendering engine or networking stack. When a user visits a maliciously crafted webpage, the attacker’s script can exploit specific edge cases in how Chrome processes cross-origin requests or DOM elements. The flaw enables the extraction of data that should be strictly confined to its original origin context. This could include cookies, local storage contents, session tokens, or other sensitive information stored by legitimate websites within the user's browser profile. The exploitation does not require elevated privileges on the host system but relies entirely on social engineering or drive-by download tactics to get the victim to load the malicious content.
The operational impact of this vulnerability is primarily centered around privacy violations and potential credential theft. By leaking cross-origin data, an attacker can gain insights into a user's browsing habits, authenticated sessions, or personal information stored across various web services. This data can be used for targeted phishing attacks, account takeover attempts, or further reconnaissance against the victim’s digital identity. Since modern web applications heavily rely on cookies and local storage for session management and state persistence, compromising these mechanisms undermines the trust model of the entire internet ecosystem. Users relying on Chrome for sensitive activities such as online banking, email access, or corporate logins are at direct risk if they do not update their browser to a patched version.
Mitigation strategies focus primarily on timely patching and defensive browsing practices. The most effective remediation is to upgrade Google Chrome to version 157.0.8103.38 or later, where the underlying flaw in the core has been addressed by the Chromium development team. For organizations managing multiple endpoints, deploying automated update policies ensures that all instances of Chrome are protected against known exploits. Additionally, users should employ browser extensions that enforce strict content security policies and block unauthorized cross-origin requests where possible. Enabling site isolation features within Chrome can also help mitigate the impact by ensuring that different origins run in separate processes, thereby limiting the ability of a compromised page to access data from other sites even if an information leak vulnerability exists.
From a classification perspective, this vulnerability aligns with CWE-200, which covers Information Exposure, specifically detailing scenarios where sensitive information is disclosed without proper authorization controls. It also relates to ATT&CK technique T1530, Data from Local System, as the attacker retrieves data stored locally on the victim's machine via browser storage mechanisms. Understanding these mappings helps security teams prioritize response efforts and align remediation actions with broader threat intelligence frameworks. Continuous monitoring for similar patterns in future updates is essential, as attackers frequently probe for variations of cross-origin information leaks to bypass evolving browser defenses.