CVE-2026-126165 Denial of service in FortiMail
Remote unauthenticated attackers can crash FortiMail by sending an attachment over SMTP that triggers excessive memory allocation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-126165?
CVE-2026-126165 is a high-severity denial of service vulnerability in Fortinet FortiMail, published on 11 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A memory allocation with excessive size value vulnerability in Fortinet FortiMail 8.0.0 through 8.0.1, FortiMail 7.6.0 through 7.6.6, FortiMail 7.4.0 through 7.4.8, FortiMail 7.2 all versions may allow a remote unauthenticated attacker to cause a denial of service via a specially crafted attachment delivered over SMTP.
Weakness: CWE-789
Which versions are affected by CVE-2026-126165?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-126165?
No fix has been published for CVE-2026-126165 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-126165 being exploited?
There is no known exploitation of CVE-2026-126165 in the wild and no public exploit code.
Sources
Also known as GHSA-24pv-pc96-gvcc.