CVE-2026-109723 Integer overflow in the Layout: Text and Fonts component
An integer overflow in the text and fonts layout component allows attackers to potentially execute arbitrary code or cause a denial of service.
- 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-2026-109723?
CVE-2026-109723 is a medium-severity 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
Integer overflow in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
Weakness: CWE-190
Which versions are affected by CVE-2026-109723?
How do I fix CVE-2026-109723?
Upgrade to a fixed version.
Is CVE-2026-109723 being exploited?
There is no known exploitation of CVE-2026-109723 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-109723, GHSA-94rc-qqr5-2gj6, UBUNTU-CVE-2026-109723.