CVE-2026-121105 in Chrome
Summary
by MITRE • 11/03/2026
Information leak in Network in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to obtain cross-origin data 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 information leak within the network stack of Google Chrome versions preceding 157.0.8103.38 represents a significant breach in browser isolation mechanisms, specifically targeting cross-origin data access. This flaw allows a remote attacker to exploit improper handling of network requests and responses, enabling them to retrieve sensitive information from web pages that should be inaccessible due to the Same-Origin Policy. The vulnerability is categorized under CWE-200, which defines Information Exposure, as it results in the unintended disclosure of confidential data to unauthorized entities. By crafting a malicious HTML page, an attacker can trigger specific network behaviors within the browser engine that bypass standard security checks, effectively allowing them to read cross-origin resources such as cookies, local storage contents, or API responses intended for other domains.
From a technical perspective, this issue likely stems from inconsistencies in how Chrome’s networking layer validates origin headers and manages resource loading contexts during asynchronous operations. When a user visits the attacker-controlled page, JavaScript code can initiate requests to target domains that are protected by strict same-origin policies. Due to the flaw, these requests may succeed or return partial data without triggering appropriate security exceptions or blocking mechanisms. This behavior undermines the fundamental web security model designed to prevent malicious sites from accessing data belonging to other trusted sites. The Chromium project has classified this vulnerability with a medium severity rating, indicating that while it does not allow for direct code execution on the victim's machine, it poses a substantial risk to user privacy and data integrity by facilitating unauthorized access to sensitive information stored within the browser context.
The operational impact of this vulnerability is primarily focused on privacy violations and potential credential theft through sophisticated phishing or drive-by download scenarios. An attacker leveraging this flaw could construct social engineering attacks where victims are lured into visiting a malicious site that silently exfiltrates data from their active sessions with other services, such as email providers, banking platforms, or corporate intranets. This capability can lead to account takeovers if session tokens are intercepted, or it can facilitate further reconnaissance by revealing internal structures and user preferences of targeted organizations. The ability to obtain cross-origin data effectively breaks the isolation boundaries that protect users from malicious web content, thereby increasing the attack surface for subsequent exploitation phases such as credential stuffing or identity theft.
To mitigate this risk, immediate action is required to update Google Chrome to version 157.0.8103.38 or later, which includes patches addressing these network stack inconsistencies. Organizations should enforce automated browser update policies across all endpoints to ensure that users are protected against known vulnerabilities in the rendering engine and networking components. Additionally, implementing Content Security Policy headers can provide an additional layer of defense by restricting the sources from which content is loaded, although this does not replace the need for patching the underlying vulnerability. Users should also exercise caution when interacting with untrusted web pages and consider using browser extensions that enhance privacy protections or block suspicious network requests. Monitoring for unusual outbound traffic patterns originating from the browser process can also aid in detecting potential exploitation attempts in real-time environments where immediate patching is not feasible.