CVE-2026-87573 describes an improper input validation vulnerability in the Network module of Google Chrome versions before 153.0.8010.36. This flaw enables a remote attacker to bypass the web origin policy by delivering a specially crafted HTML page. The web origin policy is a critical security mechanism that restricts how documents or scripts loaded from one origin can interact with resources from another origin. The vulnerability is categorized under CWE-20 (Improper Input Validation). There is no CVSS score or vendor patch advisory provided in the data, and no known exploits have been reported in the wild.

Successful exploitation could allow an attacker to bypass the web origin policy, potentially enabling unauthorized access to web resources or data that should be isolated by origin boundaries. This could lead to information disclosure or cross-origin attacks. However, the severity is assessed as medium and no active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users and administrators should monitor official Google Chrome security advisories for updates and apply the official fix once it becomes available. Until then, no specific mitigation steps are provided.