CVE-2026-126240 Auth bypass in FortiAuthenticator
An authenticated attacker controlling the upstream IdP name or SAML attribute can inject LDAP filters to bypass FortiAuthenticator authentication.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- 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-2026-126240?
CVE-2026-126240 is a high-severity authentication bypass vulnerability in Fortinet FortiAuthenticator, published on 11 Nov 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A improper neutralization of special elements used in an ldap query ('ldap injection') vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may allow an authenticated attacker to bypass authentication. Successful exploitation requires either a malicious/compromised upstream IdP, or an IdP configuration that allows the user to control the NameID (or the SAML attribute used as the username).
Weakness: CWE-90
Which versions are affected by CVE-2026-126240?
Only installations with a non-default setting turned on are exposed.
How do I fix CVE-2026-126240?
No fix has been published for CVE-2026-126240 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-2026-126240 being exploited?
There is no known exploitation of CVE-2026-126240 in the wild and no public exploit code.
Sources
Also known as GHSA-hgh4-pcf2-8q3f.