# CVE-2026-121526: Fortinet FortiAuthenticator open redirect vulnerability

Source: https://junglewise.ai/threats/cve-2026-121526-a-url-redirection-to-untrusted-site-open-redirect-vulnerability  
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-2026-121526 · Severity: medium · CVSS 6.1 · Published 2026-11-11

FortiAuthenticator is a network access and identity management appliance used to secure authentication. An attacker can craft malicious HTTP requests to redirect users to external websites, enabling credential theft, malware distribution, or social engineering attacks without requiring any authentication to exploit the vulnerability.

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

## Quick answers

**Is CVE-2026-121526 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121526 being exploited in the wild.

**How severe is CVE-2026-121526?** Medium severity, with a CVSS score of 6.1, 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, and all 6.5.x versions.

**Is there a fix for CVE-2026-121526?** 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-2026-121526 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-121526?** 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

A CWE-601 URL redirection vulnerability exists in the /login GUI endpoint of FortiAuthenticator. The flaw allows unauthenticated attackers to perform open redirect attacks by supplying crafted HTTP requests. An attacker gains the ability to redirect users to arbitrary external sites, commonly leveraged to steal credentials or distribute malware.

## Affected products

- Fortinet FortiAuthenticator 8.0.0 through 8.0.3, 6.6.0 through 6.6.10, and all 6.5.x versions

## Timeline

- 2026-11-11: disclosed: CVE-2026-121526 published

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-191](https://fortiguard.fortinet.com/psirt/FG-IR-26-191)

## 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)