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

In short

Fortinet Multiple Products has a weakness classified as authentication bypass using an alternate path or channel (CWE-288). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-01-27. NVD lists CVSS 3.1 at 9.8 CRITICAL.

What it is

“Fortinet FortiAnalyzer, FortiManager, FortiOS, and FortiProxy contain an authentication bypass using an alternate path or channel that could 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.” — CISA KEV, retrieved 2026-11-01

“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.” — NVD, retrieved 2026-11-01

Who is affected

Fortinet Multiple Products. NVD lists the following versions as affected:

• Fortinet Fortianalyzer: from 7.0.0 inclusive, through 7.0.15
• Fortinet Fortianalyzer: from 7.2.0 inclusive, through 7.2.11
• Fortinet Fortianalyzer: from 7.4.0 inclusive, before 7.4.10
• Fortinet Fortianalyzer: from 7.6.0 inclusive, before 7.6.6
• Fortinet Fortimanager: from 7.0.0 inclusive, through 7.0.15
• Fortinet Fortimanager: from 7.2.0 inclusive, through 7.2.11
• Fortinet Fortimanager: from 7.4.0 inclusive, before 7.4.10
• Fortinet Fortimanager: from 7.6.0 inclusive, before 7.6.6
• Fortinet fortinac-f: from 7.6.3 inclusive, before 7.6.6
• Fortinet Fortiproxy: from 7.0.0 inclusive, through 7.0.22
• Fortinet Fortiproxy: from 7.2.0 inclusive, through 7.2.15
• Fortinet Fortiproxy: from 7.4.0 inclusive, through 7.4.12
• Fortinet Fortiproxy: from 7.6.0 inclusive, through 7.6.4
• Fortinet Fortiweb: from 7.4.0 inclusive, through 7.4.11
• Fortinet Fortiweb: from 7.6.0 inclusive, through 7.6.6
• Fortinet Fortiweb: from 8.0.0 inclusive, through 8.0.3
• Fortinet Fortios: from 7.0.0 inclusive, through 7.0.18
• Fortinet Fortios: from 7.2.0 inclusive, through 7.2.12
• Fortinet Fortios: from 7.4.0 inclusive, before 7.4.11
• Fortinet Fortios: from 7.6.0 inclusive, before 7.6.6
• Siemens Ruggedcom ape1808 Firmware: all versions listed (no range given)

Exploitation status

CISA KEV added: 2026-01-27. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-01-30.

Scores

NVD CVSS 3.1: 9.8 CRITICAL; vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source [email protected].

EPSS by FIRST: 86.59%; percentile 99.74; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-288.

Timeline

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 KEV

What to do

• Confirm whether you run Fortinet Multiple Products and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Vendor Advisory: https://fortiguard.fortinet.com/psirt/FG-IR-26-060
• Third Party Advisory: https://cert-portal.siemens.com/productcert/html/ssa-975644.html
• Mitigation, Vendor Advisory: https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.