CVE-2026-87556 in Chrome
Summary
by MITRE • 09/09/2026
Missing authorization in Browser in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to bypass system access restrictions via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as missing authorization within the browser component of Google Chrome versions prior to 153.0.8010.36 represents a critical failure in enforcing access control policies during web content execution. This flaw allows a remote attacker, through the delivery of a specially crafted HTML page, to bypass system-level access restrictions that are typically enforced by the browser's security model. The core technical issue lies in the improper validation of user privileges or context boundaries when handling specific API calls or resource requests initiated from untrusted web content. In modern browsers, strict origin isolation and permission checks are designed to prevent malicious scripts from accessing sensitive data or performing actions on behalf of the user without explicit consent. However, in this instance, the browser failed to adequately verify whether the requesting script possessed the necessary authorization for the specific operation it was attempting to perform. This gap effectively neutralizes several layers of defense that rely on the assumption that all cross-origin requests are properly authenticated and authorized before execution proceeds.
From a technical perspective, this vulnerability falls under the category of broken access control, which is consistently ranked as one of the most significant risks in web application security by industry standards such as OWASP Top 10. Specifically, it aligns with CWE-284, Improper Access Control, where an actor is able to bypass intended restrictions on actions or resources. The exploitation vector involves a remote attacker hosting malicious HTML content that triggers specific browser behaviors without triggering the expected authorization checks. This could involve manipulating internal state variables or exploiting race conditions in permission handling logic. When such a crafted page is loaded by a victim user, the browser processes the requests as if they were authorized, potentially allowing access to private data, modification of settings, or execution of privileged commands that should have been blocked. The severity rating of Medium from Chromium indicates that while exploitation requires specific conditions and likely some level of social engineering to get the user to visit the malicious page, the impact on confidentiality and integrity can be significant depending on the context in which the browser is used.
The operational impact of this vulnerability extends beyond simple data leakage. If an attacker successfully exploits this missing authorization check, they may gain unauthorized access to sensitive information stored locally by the browser or accessible via web APIs, such as location data, clipboard contents, or authenticated session tokens. Furthermore, depending on the specific implementation details not fully disclosed in the summary, it could potentially allow for cross-site request forgery scenarios where actions are performed under the victim's identity without their knowledge. This undermines the fundamental trust model of the browser environment, where users expect that visiting a website does not compromise their system security or privacy settings. For enterprise environments relying on Chrome for secure browsing, this vulnerability poses a risk to endpoint security postures, as it provides an avenue for initial access in phishing campaigns or drive-by download attacks that target privilege escalation within the user context.
Mitigation strategies primarily involve updating the browser software to version 153.0.8010.36 or later, where these authorization checks have been corrected and strengthened. Organizations should ensure automated patch management processes are in place to deploy updates promptly upon release. Additionally, users can employ additional layers of defense such as strict content security policies implemented by website administrators, which limit the types of scripts that can run and restrict interactions with certain APIs. Browser extensions designed for enhanced privacy and security may also help mitigate some risks by blocking suspicious requests or enforcing stricter permission models than the default browser settings. Security awareness training remains crucial to prevent users from interacting with untrusted HTML content or visiting malicious sites, as technical controls alone cannot fully compensate for user interaction in social engineering attacks that leverage such vulnerabilities. The incident highlights the importance of continuous security auditing and rapid response cycles in maintaining robust web browsing environments against evolving threat landscapes aligned with tactics observed in ATT&CK frameworks related to initial access and privilege escalation via browser exploitation.