CVEs / CVE-2026-24858
CVE-2026-24858: Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability
- Known exploited in the CISA KEV catalog since 27 Jan 2026
- critical 9.8 CVSS 3.1 (from the CNA)
- EPSS 86.5% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
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.
Description
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 and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Fortinet FortiWeb | from 8.0.0, up to and including 8.0.3 | — |
| Fortinet FortiWeb | from 7.6.0, up to and including 7.6.6 | — |
| Fortinet FortiWeb | from 7.4.0, up to and including 7.4.11 | — |
| Fortinet FortiNAC-F | from 7.6.3, up to and including 7.6.5 | — |
| Fortinet FortiOS | from 7.6.0, up to and including 7.6.5 | — |
| Fortinet FortiOS | from 7.4.0, up to and including 7.4.10 | — |
| Fortinet FortiOS | from 7.2.0, up to and including 7.2.12 | — |
| Fortinet FortiOS | from 7.0.0, up to and including 7.0.18 | — |
| Fortinet FortiAnalyzer | from 7.6.0, up to and including 7.6.5 | — |
| Fortinet FortiAnalyzer | from 7.4.0, up to and including 7.4.9 | — |
| Fortinet FortiAnalyzer | from 7.2.0, up to and including 7.2.11 | — |
| Fortinet FortiAnalyzer | from 7.0.0, up to and including 7.0.15 | — |
| Fortinet FortiProxy | from 7.6.0, up to and including 7.6.4 | — |
| Fortinet FortiProxy | from 7.4.0, up to and including 7.4.12 | — |
| Fortinet FortiProxy | from 7.2.0, up to and including 7.2.15 | — |
| Fortinet FortiProxy | from 7.0.0, up to and including 7.0.22 | — |
| Fortinet FortiManager | from 7.6.0, up to and including 7.6.5 | — |
| Fortinet FortiManager | from 7.4.0, up to and including 7.4.9 | — |
| Fortinet FortiManager | from 7.2.0, up to and including 7.2.11 | — |
| Fortinet FortiManager | from 7.0.0, up to and including 7.0.15 | — |
| Siemens RUGGEDCOM APE1808 | all versions | — |
Exploitation
| In CISA KEV since | 27 Jan 2026 |
|---|---|
| Due date for US federal agencies | 30 Jan 2026 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 9.8 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-288 |
References
- CVE-2026-24858 on NVD
- CVE-2026-24858 in the CISA KEV catalog
- https://fortiguard.fortinet.com/psirt/FG-IR-26-060 (cited by CISA)
- https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios (cited by CISA)
- https://fortiguard.fortinet.com/psirt/FG-IR-26-060 Vendor Advisory
- https://cert-portal.siemens.com/productcert/html/ssa-975644.html Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24858 US Government Resource
- https://www.fortinet.com/blog/psirt-blogs/analysis-of-sso-abuse-on-fortios Mitigation, Vendor Advisory
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
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