CVE-2026-78903 Security feature bypass in Chrome

What is CVE-2026-78903?

CVE-2026-78903 is a low-severity vulnerability in Google Chrome, published on 25 Aug 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

Incomplete cleanup in SiteIsolation in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: Medium)

Weakness: CWE-459

Which versions are affected by CVE-2026-78903?

It affects 1 product.

Products include Google Chrome.

How do I fix CVE-2026-78903?

Upgrade to a fixed version.

Is CVE-2026-78903 being exploited?

There is no known exploitation of CVE-2026-78903 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-2026-78903, ECHO-530e-5606-6b51, GHSA-q5r9-8rpf-9h3p, MINI-mc7q-8xw6-wf6r.