FG-IR-25-667: Request smuggling attack in FortiOS

Published Feb 10, 2026
·
Updated

An HTTP request smuggling vulnerability [CWE-444] in FortiOS may allow an unauthenticated attacker to smuggle an unlogged http request through the firewall policies via a specially crafted header

Affected Software

5 affected componentsFixes available
Fortinet FortiOS=.
Fortinet FortiOS>=7.4.0<=7.4.9
Fortinet FortiOS>=7.2
Fortinet FortiOS>=7.0
Fortinet FortiOS>=6.4.3<=6.4.16

Event History

Feb 10, 2026
Advisory Published
via FortiGuard·12:00 AM
Data Sourced
via FortiGuard·12:00 AM
DescriptionSeverityWeaknessAffected Software
Feb 26, 2026
Advisory Published
via FortiGuard·03:25 PM
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Frequently Asked Questions

1

What is the severity of FG-IR-25-667?

The FG-IR-25-667 vulnerability is considered critical due to its potential for unauthorized access and data compromise.

2

How do I fix FG-IR-25-667?

To mitigate the FG-IR-25-667 vulnerability, update FortiOS to versions 7.6.1 or 7.4.10 and above, or apply vendor patches as recommended.

3

What types of attackers can exploit FG-IR-25-667?

FG-IR-25-667 can be exploited by unauthenticated attackers who can craft malicious HTTP requests.

4

Which FortiOS versions are affected by FG-IR-25-667?

FG-IR-25-667 affects multiple FortiOS versions including 7.0, 7.2, and 6.4.3 to 6.4.16.

5

Is there a known workaround for FG-IR-25-667?

Currently, there are no specific workarounds for FG-IR-25-667 other than upgrading to a patched version of FortiOS.

Contact

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