CVE-2026-109753 Incorrect boundary conditions in the Layout component
Incorrect boundary conditions in the Layout component allow attackers to cause memory corruption, potentially leading to code execution or crashes.
- 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-2026-109753?
CVE-2026-109753 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
Incorrect boundary conditions in the Layout component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
Weakness: CWE-119
Which versions are affected by CVE-2026-109753?
How do I fix CVE-2026-109753?
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-2026-109753 being exploited?
There is no known exploitation of CVE-2026-109753 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-109753, GHSA-qrr3-f9g6-cf9g, UBUNTU-CVE-2026-109753.