CVE-2026-66313 Microsoft Edge (Chromium-based) Tampering Vulnerability

Medium 6.8 Published Updated

An origin validation error in Microsoft Edge allows local attackers to tamper with data, bypassing security controls.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Local or same network only
Victim action needed
Not needed
Fix
None listed

What is CVE-2026-66313?

CVE-2026-66313 is a medium-severity vulnerability in Microsoft Edge Chromium, published on 3 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to perform tampering locally.

Weakness: CWE-346

Which versions are affected by CVE-2026-66313?

It affects 1 product.

Products include Microsoft Edge Chromium.

How do I fix CVE-2026-66313?

No fix has been published for CVE-2026-66313 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-66313 being exploited?

There is no known exploitation of CVE-2026-66313 in the wild and no public exploit code.

All Microsoft Edge Chromium vulnerabilities

Sources

Also known as GHSA-8q78-vm89-wh64.

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