CVE-2026-11288 in Chrome
Summary
by MITRE • 06/05/2026
Insufficient policy enforcement 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: Low)
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Analysis
by VulDB Data Team • 06/05/2026
This vulnerability represents a cross-site scripting policy enforcement weakness in Google Chrome's CSS handling mechanism that existed prior to version 149.0.7827.53. The issue stems from inadequate enforcement of same-origin policy restrictions within the browser's cascading style sheets implementation, creating a potential avenue for remote attackers to exploit cross-origin data leakage through maliciously crafted HTML content. The vulnerability specifically affects how Chrome processes CSS rules and style declarations when encountering cross-origin resources, allowing attackers to bypass expected security boundaries that should prevent unauthorized access to data from different origins.
The technical flaw manifests in Chrome's CSS parser and rendering engine where certain CSS properties and selectors fail to properly validate origin boundaries when processing external resources. Attackers can construct HTML pages containing specific CSS rules that trigger unintended behavior in the browser's rendering pipeline, potentially enabling them to access or infer information about resources loaded from different origins. This type of vulnerability falls under the CWE-693 category of Protection Mechanism Failure, specifically relating to inadequate enforcement of access control policies. The flaw operates at the intersection of web security boundaries where CSS processing should maintain strict isolation between different origins, but instead allows for potential information disclosure through crafted styling instructions.
The operational impact of this vulnerability extends beyond simple data leakage to potentially enable more sophisticated attacks including user tracking, session information harvesting, and cross-origin resource enumeration. An attacker could leverage this weakness to gather sensitive information about user browsing patterns, access control mechanisms, or even extract data from authenticated sessions that should remain isolated between different domains. The low severity classification does not diminish the potential for exploitation in combination with other vulnerabilities or in specific attack scenarios. This vulnerability aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments and could be exploited as part of a broader attack chain targeting web browsers and their security mechanisms.
Mitigation strategies for this vulnerability require immediate browser updates to versions 149.0.7827.53 and later where the CSS policy enforcement has been strengthened. Organizations should implement comprehensive browser security policies that include regular update schedules and monitoring for outdated browser versions in their environments. Additional defensive measures include implementing strict content security policies that limit cross-origin resource loading and monitoring for suspicious CSS behavior in web applications. Network-level protections such as web application firewalls and intrusion detection systems can help identify and block exploitation attempts targeting this specific vulnerability. The fix addresses the root cause by strengthening the origin validation checks within Chrome's CSS processing pipeline, ensuring that all CSS operations properly enforce same-origin restrictions regardless of the complexity or sophistication of the attacking HTML page structure.