CVE-2026-126155 Auth bypass in FortiMail
Unauthenticated remote attackers can obtain any IBE recipient's authenticated webmail session in FortiMail and read or send their encrypted mail.
- 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-2026-126155?
CVE-2026-126155 is a critical authentication bypass 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 incorrect authorization 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 an unauthenticated remote attacker to obtain an authenticated IBE webmail session as any IBE recipient and read or send their encrypted mail via crafted HTTP requests.
Weakness: CWE-863
Which versions are affected by CVE-2026-126155?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-126155?
No fix has been published for CVE-2026-126155 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-126155 being exploited?
There is no known exploitation of CVE-2026-126155 in the wild and no public exploit code.
Sources
Also known as GHSA-4pf4-qxrv-h22x.