CVE-2026-91740 in Chrome
Summary
by MITRE • 09/15/2026
Uninitialized resource in Skia in Google Chrome prior to 153.0.8010.47 allowed a remote attacker to obtain cross-origin data via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified within the Skia graphics library, which serves as the core rendering engine for Google Chrome prior to version 153.0.8010.47, represents a critical failure in memory management and resource initialization protocols. This flaw is classified fundamentally as an uninitialized resource error, where specific data structures or object states are accessed before they have been properly initialized with valid values. In the context of browser security architecture, such errors often lead to undefined behavior that can be exploited by malicious actors to bypass standard isolation mechanisms. The severity rating of High from Chromium indicates that this is not merely a theoretical issue but one capable of causing significant compromise to user data integrity and confidentiality under realistic attack scenarios involving crafted web content.
From a technical perspective, the Skia library handles complex graphical operations including text rendering, image processing, and vector graphics composition. When an HTML page containing specially constructed elements triggers specific code paths within Skia, the application may attempt to read or manipulate memory locations that have not been zeroed out or assigned default values by preceding initialization routines. This lack of proper state setup means that the content of these uninitialized memory regions is determined by whatever data previously occupied those addresses in the process space. If an attacker can control the execution flow leading up to this access point, they may be able to influence what data is read from these uninitialized slots or cause the application to behave unpredictably based on stale information left over from previous operations within the same memory context.
The operational impact of this vulnerability centers on the potential for cross-origin data leakage, a severe breach of the Same-Origin Policy that forms the bedrock of web security. By exploiting the uninitialized resource flaw, a remote attacker hosting or directing traffic to a crafted HTML page can potentially read sensitive information belonging to other origins loaded within the same browser instance. This could include cookies, local storage contents, session tokens, or dynamically generated content from trusted websites such as banking portals or email services. The ability to exfiltrate cross-origin data effectively neutralizes the isolation between different web applications running in the same tab or window, allowing an attacker to perform actions on behalf of the user without their knowledge or consent, thereby facilitating account takeover and identity theft scenarios.
This type of vulnerability aligns closely with Common Weakness Enumeration (CWE) identifiers such as CWE-457, which describes the use of an uninitialized variable, and potentially CWE-200, concerning exposure of sensitive information to an unauthorized actor. In terms of offensive security frameworks like MITRE ATT&CK, this exploitation technique falls under techniques related to data exfiltration over a different network or protocol than initially established, specifically leveraging browser-based side channels or memory corruption to bypass origin boundaries. The attack vector is classified as remote because it requires no user interaction beyond visiting the malicious webpage, making it highly scalable for phishing campaigns and drive-by download attacks that rely on social engineering to lure victims into triggering the exploit code embedded in the HTML structure.
Mitigation strategies primarily involve applying the vendor-provided patch immediately upon availability, which updates the Skia library within Chrome to version 153.0.8010.47 or later. This update includes fixes that ensure all relevant resources are properly initialized before being accessed during rendering operations. For organizations managing large fleets of endpoints, automated deployment tools should be utilized to enforce this patching cycle rapidly. Additionally, users can employ browser hardening techniques such as disabling JavaScript for untrusted sites via extensions like NoScript or using strict content security policies if they control the web applications themselves. While these measures do not fix the underlying engine flaw, they reduce the attack surface by limiting the ability of malicious scripts to execute complex rendering operations that might trigger the vulnerability. Continuous monitoring for anomalous network traffic originating from browser processes can also help detect potential exploitation attempts in real-time before significant data loss occurs.