CVE-2026-9903 Security feature bypass in Chrome

What is CVE-2026-9903?

CVE-2026-9903 is a medium-severity vulnerability in Google Chrome, published on 28 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Insufficient validation of untrusted input in Site Isolation in Google Chrome prior to 148.0.7778.216 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted MHTML page. (Chromium security severity: High)

Weakness: CWE-20

Which versions are affected by CVE-2026-9903?

It affects 1 product.

Products include Google Chrome.

How do I fix CVE-2026-9903?

Upgrade to a fixed version.

Is CVE-2026-9903 being exploited?

There is no known exploitation of CVE-2026-9903 in the wild and no public exploit code.

Other vulnerabilities in Google Chrome

• CVE-2022-4135 Google Chromium GPU Heap Buffer Overflow Exploited Critical 9.6
• CVE-2020-16017 Google Chrome Use-After-Free Exploited Critical 9.6
• CVE-2020-16010 Google Chrome for Android UI Heap Buffer Overflow Exploited Critical 9.6
• CVE-2026-87491 Google Chromium V8 Out of Bounds Write Exploited High 8.8
• CVE-2026-85046 Google Chromium V8 Type Confusion Exploited High 8.8

All Google Chrome vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-9903, ECHO-a824-1448-6af1, GHSA-5f28-4vhp-7f3h, MINI-7p43-835x-4x6v.