CVE-2026-109712 Sandbox escape due to uninitialized memory in the Graphics component
An attacker can escape the sandbox and execute arbitrary code via uninitialized memory in the Graphics component of Firefox and Thunderbird.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-109712?
CVE-2026-109712 is a high-severity memory corruption vulnerability in Mozilla Firefox, published on 13 Oct 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
Sandbox escape due to uninitialized memory in the Graphics component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
Weakness: CWE-908
Which versions are affected by CVE-2026-109712?
How do I fix CVE-2026-109712?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-109712 being exploited?
There is no known exploitation of CVE-2026-109712 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-109712, GHSA-qprj-mxfp-87w7, UBUNTU-CVE-2026-109712.