CVE-2026-92034 Site isolation issue in the Graphics component

Critical 9.1 Published Updated

A site isolation flaw in the Graphics component allows bypassing security boundaries, affecting Firefox and Thunderbird users.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Over the internet
Victim action needed
Not needed
Fix
Available

What is CVE-2026-92034?

CVE-2026-92034 is a critical vulnerability in Mozilla Firefox, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Site isolation issue in the Graphics component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

Weakness: CWE-346

Which versions are affected by CVE-2026-92034?

It affects 2 products.

Products include Mozilla Firefox, Mozilla Thunderbird.

How do I fix CVE-2026-92034?

Upgrade to a fixed version.

Is CVE-2026-92034 being exploited?

There is no known exploitation of CVE-2026-92034 in the wild and no public exploit code.

All Mozilla Firefox vulnerabilities

Sources

Also known as GHSA-3mrv-rm2p-hfgx, UBUNTU-CVE-2026-92034.

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