CVE-2026-11155 in Chrome
Summary
by MITRE • 06/05/2026
Inappropriate implementation in CSS in Google Chrome prior to 149.0.7827.53 allowed a remote attacker to leak cross-origin data via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 06/05/2026
This vulnerability represents a cross-origin resource sharing flaw in Google Chrome's CSS implementation that could potentially allow remote attackers to access sensitive data from different origins. The issue stems from improper handling of CSS properties and their interaction with cross-origin resources, creating a pathway for information disclosure attacks. The vulnerability affects Chrome versions prior to 149.0.7827.53 and is classified as medium severity by Chromium security standards, indicating a significant risk to user privacy and data confidentiality. The flaw specifically manifests in how Chrome processes certain CSS elements when loading content from different origins, potentially exposing internal data structures or cached information to malicious actors. This type of vulnerability falls under the broader category of cross-origin information leakage, which is particularly concerning in modern web browsers where numerous security boundaries exist between different content sources. The vulnerability is particularly dangerous because it operates at the CSS rendering level, which is fundamental to how web pages are displayed and structured, making it difficult to detect and prevent through traditional security measures.
The technical implementation flaw involves how Chrome's CSS engine manages cross-origin resource access during page rendering. When processing crafted HTML pages containing specific CSS properties, the browser fails to properly enforce same-origin policies that should prevent unauthorized access to resources from different domains. This misimplementation allows attackers to construct malicious web pages that can indirectly access or infer information about resources loaded from other origins. The vulnerability is particularly insidious because it leverages legitimate CSS functionality to achieve unauthorized data access, making it challenging to distinguish between normal browser behavior and malicious exploitation attempts. The attack vector typically involves crafting HTML documents with specific CSS rules that trigger the flawed behavior when rendered in the affected browser versions. This type of vulnerability is categorized under CWE-200 (Information Exposure) and aligns with ATT&CK technique T1557 (Adversary-in-the-Middle) as it enables unauthorized data collection through legitimate browser mechanisms. The flaw demonstrates a failure in Chrome's security model to properly isolate cross-origin CSS processing, creating an unexpected information flow that violates fundamental web security principles.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially enabling more sophisticated attacks that could compromise user privacy and system integrity. Attackers could exploit this flaw to gather sensitive information about users' browsing activities, cached resources, or even internal system details that should remain isolated between different origins. The medium severity classification indicates that while the vulnerability may not allow complete system compromise, it represents a significant risk to user confidentiality and could serve as a stepping stone for more advanced attacks. Organizations using affected Chrome versions face potential exposure to cross-origin data leakage attacks that could be particularly damaging in environments where sensitive information is handled. The vulnerability affects all users of the affected Chrome versions and requires immediate attention to prevent exploitation. Security professionals must understand that this type of vulnerability can be particularly challenging to remediate because it involves complex interactions between CSS rendering and security boundaries, requiring careful analysis of how different browser components interact with cross-origin resources.
Mitigation strategies for this vulnerability should focus on immediate Chrome updates to versions 149.0.7827.53 or later, where the implementation flaw has been addressed. Organizations should implement comprehensive browser security monitoring to detect potential exploitation attempts and ensure all users are promptly updated to secure versions. Additional protective measures include deploying web application firewalls that can detect and block malicious CSS patterns, implementing strict content security policies to limit cross-origin resource access, and conducting regular security audits of web applications to identify potential exploitation vectors. Security teams should also consider implementing browser hardening measures such as disabling unnecessary CSS features, using sandboxing techniques, and monitoring for unusual cross-origin resource access patterns. The vulnerability highlights the importance of continuous security testing and monitoring of browser components, particularly those that handle cross-origin operations. Regular security assessments should include testing for similar implementation flaws in CSS processing and other browser rendering components to prevent similar vulnerabilities from being exploited in the future. Organizations should also maintain awareness of Chromium security advisories and ensure rapid deployment of security patches to protect against known vulnerabilities in their browser environments.