Fortinet PSIRT AdvisoriesFG-IR-26-170

JWT used for authentication in web GUI signed with static key

CVSSv3 Score: 9.6 An Inclusion of Sensitive Information in Source Code vulnerability [CWE-540] in FortiMonitorOnSight web portal may allow a remote unauthenticated attacker to bypass authentication via forged or reused JWT Revised on 2026-09-08 00:00:00

Read the vendor bulletin Get alerts for FortiMonitorOnSight

9.6CVSS out of 10Critical severity

Scope

What the vendor says is affected

FortiMonitorOnSight

Timeline

When this advisory changed

Sep 8, 2026 at 7:00 AM UTC
Published by Fortinet
The publication date reported by the vendor.
Sep 8, 2026 at 5:10 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 13, 2026 at 4:50 AM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Source

Start with the vendor's bulletin

SecurityAlert organizes the fields the vendor published. The original bulletin remains the source of record for affected versions, fixes, and later changes.

Vendor: Fortinet
Advisory ID: FG-IR-26-170
Last source check: Sep 13, 2026 at 4:50 AM UTC

Open the official bulletin How SecurityAlert builds this record

Your environment

Check the systems you actually run

A vendor advisory can tell you what may be affected. It cannot tell you whether that product and version are installed in your environment.

Confirm the product and installed version.
Read the vendor's prerequisites and exceptions.
Test the update or mitigation through your normal change process.

Watch FortiMonitorOnSight

Keep following

Get new Fortinet advisories

Use the vendor-specific RSS feed or set up alerts for a product your team relies on.

Follow this vendor's RSS feed

What the vendor says is affected

When this advisory changed

Related advisories from Fortinet

ZTNA Portal Improper Certificate Validation

Workflow session email approval process bypass

Uncontrolled Resource Consumption in SNMP

Unauthenticated Control of NAT Rules Leading to Exposure of Sensitive Information

Open Redirect on FortiSIEM

Null Pointer Dereference in Log Report