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A incorrect authorization vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may…

Affects Fortinet FortiAuthenticator 8.0.0 through 8.0.3 and 6.6.0 through 6.6.10, where an incorrect authorization flaw may allow authentication bypass. Fixed in 8.0.4.

CVE-2026-126251EUVD-2026-123895

Written by anthropic/claude-sonnet-5.5 from the sources below. Verify against them.

9.1CriticalCNA
Exploited
No known exploitation
Fix
Fixed in 8.0.4
Who is exposed
Not reported

Do first: Upgrade to a fixed version: 8.0.4.

Published
Last modified
Reference
Last checked
40/100 · provisional
Unclear
None on Exploit-DB, Metasploit or GitHub
On X
View the cve.now post

Summary

An incorrect authorization flaw in Fortinet FortiAuthenticator lets an attacker bypass authentication and gain unauthorized access. It can be reached remotely over the network, without logging in or any action from a user.

Read the original description

A incorrect authorization vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may allow an attacker to bypass authentication and gain unauthorized access.

Who should check

Teams running Fortinet FortiAuthenticator 8.0.0 through 8.0.3 or 6.6.0 through 6.6.10, including identity and access management and network security teams.

Read the source excerpt

“FortiAuthenticator 8.0 8.0.0 through 8.0.3”

fortiguard.fortinet.com

cve.now Index

40Pcve.now Index 40 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
  • Reach14/20Affects Fortinet (an enterprise product or network appliance)
  • Severity9.1/10CVSS 9.1
  • No patch0/5No signal

What would change the score

  • Would score about 85 if added to CISA KEV
  • Would score about 80 if CISA's SSVC rates exploitation active
  • Would score about 45 if advisories confirm default setups are exposed

What to do

  • Upgrade to a fixed version: 8.0.4.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-126251 (A incorrect authorization vulnerability in Fortinet FortiAuthenticator 8.0.0 through 8.0.3, FortiAuthenticator 6.6.0 through 6.6.10 may…), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-126251 (entry last updated 2026-11-11):
Affected:
- Fortinet FortiAuthenticator: from 8.0.0, through 8.0.3; from 6.6.0, through 6.6.10
Fixed versions: 8.0.4.
Conditions (all must be true for the bug to be hit):
- Running FortiAuthenticator 8.0.0 through 8.0.3 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-265)
- Running FortiAuthenticator 6.6.0 through 6.6.10 (source: https://fortiguard.fortinet.com/psirt/FG-IR-26-265)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-126251 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126251 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://fortiguard.fortinet.com/psirt/FG-IR-26-265
- https://www.cve.org/CVERecord?id=CVE-2026-126251
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126251
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126251"}.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. Posted on X by cve.now

Affected versions

  • Fortinet FortiAuthenticator

    From 8.0.0 · through 8.0.3; From 6.6.0 · through 6.6.10

Evidence 3

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Link

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-126251

Is CVE-2026-126251 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

What does this mean?

An incorrect authorization flaw in FortiAuthenticator may allow an attacker to bypass authentication and gain unauthorized access.Source: fortiguard.fortinet.com, cve.org

Which versions are affected by CVE-2026-126251?

FortiAuthenticator: from 8.0.0 through 8.0.3; from 6.6.0 through 6.6.10.Source: cve.now feed data

Am I affected, and how do I check?

FortiAuthenticator 8.0.0 through 8.0.3 and 6.6.0 through 6.6.10 are listed as affected. The installed version can be checked in the FortiAuthenticator administration interface and compared against these ranges.Source: fortiguard.fortinet.com, cve.org

How do I fix CVE-2026-126251?

The advisory says to upgrade to FortiAuthenticator version 8.0.4 or above. No workaround is given in the facts.Source: fortiguard.fortinet.com, cve.org