# CVE-2026-126237: Fortinet FortiAuthenticator infinite loop denial of service

Source: https://junglewise.ai/threats/cve-2026-126237-a-loop-with-unreachable-exit-condition-infinite-loop  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-126237 · Severity: high · CVSS 7.5 · Published 2026-11-11

FortiAuthenticator is an authentication and identity management platform used by enterprises to control access to corporate resources. An attacker can send specially crafted network requests to trigger an infinite loop in the API, causing the service to hang and become unavailable to legitimate users. No authentication is required to exploit this vulnerability.

Technologies: [Fortinet FortiAuthenticator](https://junglewise.ai/threats/technologies/fortiauthenticator). Vendors: [Fortinet](https://junglewise.ai/threats/vendors/fortinet).

## Quick answers

**Is CVE-2026-126237 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126237 being exploited in the wild.

**How severe is CVE-2026-126237?** High severity, with a CVSS score of 7.5, published 11 November 2026.

**Which products and versions are affected?** Fortinet FortiAuthenticator 8.0.0 through 8.0.3, 6.6.0 through 6.6.10.

**Is there a fix for CVE-2026-126237?** Yes: fixed in FortiAuthenticator 8.0.4 or above, 6.6.11 or above. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126237 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-126237?** Check whether you run Fortinet FortiAuthenticator at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in FortiAuthenticator 8.0.4 or above, 6.6.11 or above

## Technical details

An infinite loop condition exists in the FortiAuthenticator API component (CWE-835) due to an unreachable exit condition. An unauthenticated attacker can send crafted TCP requests over the network to trigger this loop, causing denial of service. The vulnerability affects versions 8.0.0–8.0.3 and 6.6.0–6.6.10, with patches available in 8.0.4+ and 6.6.11+.

## Affected products

- Fortinet FortiAuthenticator 8.0.0 through 8.0.3, 6.6.0 through 6.6.10

## Timeline

- 2026-11-10: disclosed
- 2026-11-11: advisory

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-252](https://fortiguard.fortinet.com/psirt/FG-IR-26-252)

## Related threats

- [Fortinet FortiAuthenticator hard-coded password authentication bypass](https://junglewise.ai/threats/cve-2026-126257-a-use-of-hard-coded-password-vulnerability-in-fortinet)
- [Fortinet FortiAuthenticator SQL injection](https://junglewise.ai/threats/cve-2026-126252-a-improper-neutralization-of-special-elements-used-in-an-sql)
- [Fortinet FortiAuthenticator incorrect authorization](https://junglewise.ai/threats/cve-2026-126251-a-incorrect-authorization-vulnerability-in-fortinet)
- [Fortinet FortiAuthenticator authorization bypass DoS](https://junglewise.ai/threats/cve-2026-126250-a-incorrect-authorization-vulnerability-in-fortinet)
- [Fortinet FortiAuthenticator privilege escalation in GUI](https://junglewise.ai/threats/cve-2026-126249-a-improper-privilege-management-vulnerability-in-fortinet)