Security Digest · Vulnerability record · Known exploited
CVE-2026-24858: Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel Vulnerability
Exploited in the wild (CISA KEV). 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…
CISA KEV · added 2026-01-27 CVSS 9.4 Critical EPSS 85.8% · p99.7 Act now
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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.
CISA’s 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.
Weakness type: CWE-288.
Product: Fortinet Multiple Products · Assigned by: fortinet · Published: 2026-01-27
Affected and fixed versions
| Vendor | Product | Affected versions (per 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 scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| fortinet | 3.1 | 9.4 Critical | 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 |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CVE record published by fortinet
- — erroneo.us brief: FortiCloud SSO Cross-Account Login: CVE-2026-24858
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- fortinet.com fortinet.com
- Listed in CISA KEV notes (fortiguard.fortinet.com) fortiguard.fortinet.com
Vulnerability records
- CVE.org record CVE-2026-24858 cve.org
- NVD entry CVE-2026-24858 nvd.nist.gov
Government
Other references from the CVE record and advisory
- cert-portal.siemens.com cert-portal.siemens.com
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