---
title: "CVE-2026-24858: Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-24858/
description: "CVE-2026-24858 (Fortinet Multiple Products): Exploited in the wild (CISA KEV). An Authentication Bypass Using an Alternate Path or Channel vulnerability…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-01-27
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-24858"
kev: true
cvss: 9.4
epss: 0.85796
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-24858: Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Fortinet Multiple Products. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-01-27, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-01-30 ; treat that as the outer limit, not the target.
- EPSS 85.8% , percentile 99.7: FIRST’s model estimates a 85.8% chance of exploitation activity in the next 30 days, higher than 99.7% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Act now. FortiCloud SSO Cross-Account Login: CVE-2026-24858 — Any Fortinet device that relies on FortiCloud SSO needs the January 2026 builds (FortiCloud now refuses SSO from vulnerable versions anyway), and any device with SSO enabled before then should be checked for rogue admins.

## What it is

An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] vulnerability in Fortinet FortiAnalyzer 7.6.0 through 7.6.5, FortiAnalyzer 7.4.0 through 7.4.9, FortiAnalyzer 7.2.0 through 7.2.11, FortiAnalyzer 7.0.0 through 7.0.15, FortiManager 7.6.0 through 7.6.5, FortiManager 7.4.0 through 7.4.9, FortiManager 7.2.0 through 7.2.11, FortiManager 7.0.0 through 7.0.15, FortiNAC-F 7.6.3 through 7.6.5, FortiOS 7.6.0 through 7.6.5, FortiOS 7.4.0 through 7.4.10, FortiOS 7.2.0 through 7.2.12, FortiOS 7.0.0 through 7.0.18, FortiProxy 7.6.0 through 7.6.4, FortiProxy 7.4.0 through 7.4.12, FortiProxy 7.2.0 through 7.2.15, FortiProxy 7.0.0 through 7.0.22, FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.

## Affected products (CVE record)

- Fortinet FortiWeb: 8.0.0 <= 8.0.3, 7.6.0 <= 7.6.6, 7.4.0 <= 7.4.11
- Fortinet FortiNAC-F: 7.6.3 <= 7.6.5
- Fortinet FortiOS: 7.6.0 <= 7.6.5, 7.4.0 <= 7.4.10, 7.2.0 <= 7.2.12, 7.0.0 <= 7.0.18
- Fortinet FortiAnalyzer: 7.6.0 <= 7.6.5, 7.4.0 <= 7.4.9, 7.2.0 <= 7.2.11, 7.0.0 <= 7.0.15
- Fortinet FortiProxy: 7.6.0 <= 7.6.4, 7.4.0 <= 7.4.12, 7.2.0 <= 7.2.15, 7.0.0 <= 7.0.22
- Fortinet FortiManager: 7.6.0 <= 7.6.5, 7.4.0 <= 7.4.9, 7.2.0 <= 7.2.11, 7.0.0 <= 7.0.15

## Severity

- fortinet CVSS 3.1: 9.4 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C`

## Exploitation

- CISA KEV: added 2026-01-27; federal due date 2026-01-30. Known ransomware use: Unknown.
- CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 85.80% probability of exploitation activity in the next 30 days; percentile 99.7.

## Sources

- [fortinet.com](https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios)
- [Listed in CISA KEV notes (fortiguard.fortinet.com)](https://fortiguard.fortinet.com/psirt/FG-IR-26-060)
- [CVE.org record CVE-2026-24858](https://www.cve.org/CVERecord?id=CVE-2026-24858)
- [NVD entry CVE-2026-24858](https://nvd.nist.gov/vuln/detail/CVE-2026-24858)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24858)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-975644.html)

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Source page: https://erroneo.us/security/cve/CVE-2026-24858/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt