# CVE-2026-126151: Fortinet FortiMail authentication algorithm bypass

Source: https://junglewise.ai/threats/cve-2026-126151-a-incorrect-implementation-of-authentication-algorithm  
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-2026-126151 · Severity: high · CVSS 7.5 · Published 2026-11-11

FortiMail is an email security appliance that protects organizations from email-borne threats. An incorrect implementation of its authentication algorithm allows unauthenticated remote attackers to take over user accounts and gain unauthorized access to email systems. This is a critical issue since the attacker needs no credentials to exploit it.

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

## Quick answers

**Is CVE-2026-126151 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126151 being exploited in the wild.

**How severe is CVE-2026-126151?** High severity, with a CVSS score of 7.5, published 11 November 2026.

**Which products and versions are affected?** Fortinet FortiMail 8.0.0 through 8.0.1, 7.6.0 through 7.6.6, 7.4.0 through 7.4.8, 7.2 all versions.

**Is there a fix for CVE-2026-126151?** Yes: fixed in FortiMail 8.0.2, 7.6.7, 7.4.9. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126151 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-126151?** Check whether you run Fortinet FortiMail 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 FortiMail 8.0.2, 7.6.7, 7.4.9

## Technical details

An incorrect implementation of the authentication algorithm (CWE-303) in FortiMail's API component allows unauthenticated remote attackers to bypass authentication via a crafted request, leading to account takeover and privilege escalation. The vulnerability affects multiple versions across multiple release branches with no precondition other than network access. Fortinet has released patches for all supported versions.

## Affected products

- Fortinet FortiMail 8.0.0 through 8.0.1, 7.6.0 through 7.6.6, 7.4.0 through 7.4.8, 7.2 all versions

## Timeline

- 2026-11-10: disclosed: Initial publication
- 2026-10-05: patched: FortiMail Cloud updated to v7.6.7 GA or v8.0.2 GA

## References

- [https://fortiguard.fortinet.com/psirt/FG-IR-26-203](https://fortiguard.fortinet.com/psirt/FG-IR-26-203)

## Related threats

- [Fortinet FortiMail SQL injection](https://junglewise.ai/threats/cve-2026-126263-a-improper-neutralization-of-special-elements-used-in-an-sql)
- [Fortinet FortiMail argument injection in administrative interface](https://junglewise.ai/threats/cve-2026-126169-a-improper-neutralization-of-argument-delimiters-in-a-command)
- [Fortinet FortiMail argument injection in administrative interface](https://junglewise.ai/threats/cve-2026-126168-a-improper-neutralization-of-argument-delimiters-in-a-command)
- [Fortinet FortiMail command injection in admin GUI](https://junglewise.ai/threats/cve-2026-126167-a-improper-neutralization-of-special-elements-used-in-a-command)
- [Fortinet FortiMail argument injection in admin interface](https://junglewise.ai/threats/cve-2026-126166-a-improper-neutralization-of-argument-delimiters-in-a-command)