EUVD-2026-27993Severity by source
AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
Lifecycle Timeline
3DescriptionCVE.org
Insufficient validation of untrusted input in COOP in Google Chrome prior to 148.0.7778.96 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: Medium)
AnalysisAI
Insufficient validation of Cross-Origin-Opener-Policy (COOP) headers in Google Chrome prior to version 148.0.7778.96 allows a remote attacker with a compromised renderer process to bypass site isolation protections via a crafted HTML page. The vulnerability requires renderer compromise and user interaction, limiting real-world exploitation to targeted attacks against users whose Chrome renderer is already under attacker control. Chromium rates the security severity as Medium; vendor patch is available.
Technical ContextAI
The vulnerability exists in Chrome's Cross-Origin-Opener-Policy (COOP) header handling, a web platform security feature designed to isolate browsing contexts and enforce site isolation at the renderer level. COOP is a HTTP response header that controls whether a document can be opened in a popup or accessed by another document via the window.opener property. CWE-20 (Improper Input Validation) indicates that the renderer process fails to properly validate COOP directives in crafted HTML, allowing an attacker who has already compromised the renderer to construct a malicious page that bypasses the intended isolation boundaries. Site isolation is Chrome's multi-process architecture defense that runs each site in its own process; COOP enforcement is a critical component of this isolation model.
RemediationAI
Upgrade Google Chrome to version 148.0.7778.96 or later via the automatic update mechanism (Settings > About Chrome) or manually download from https://www.google.com/chrome/. Users on Chrome's stable channel will receive the update automatically; enterprise deployments should verify rollout via the Chrome Enterprise release schedule at https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop.html. No workarounds are available for users whose renderer process is already compromised; mitigation depends on patching. Organizations cannot selectively disable COOP validation without exposing to other site isolation bypasses.
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Same weakness CWE-20 – Improper Input Validation
View allSame technique Authentication Bypass
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External POC / Exploit Code
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