CVE-2026-100801 Privilege escalation in the DLL Services component
An attacker can escalate privileges via the DLL Services component in Mozilla 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-2026-100801?
CVE-2026-100801 is a high-severity vulnerability in Mozilla Firefox, published on 29 Sep 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
Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159, Thunderbird 153.6, Firefox 157, and Firefox ESR 140.17.
Weakness: CWE-269
Which versions are affected by CVE-2026-100801?
It affects 2 products.
Products include Mozilla Firefox, Mozilla Thunderbird.
How do I fix CVE-2026-100801?
Upgrade to a fixed version.
Is CVE-2026-100801 being exploited?
There is no known exploitation of CVE-2026-100801 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as DEBIAN-CVE-2026-100801, GHSA-7f52-cp5w-7wmh, UBUNTU-CVE-2026-100801.