Fortinet Multiple Products Authentication Bypass Using an Alternate Path or Channel
CVE-2026-24858 is a critical-severity authentication bypass using an alternate path or channel vulnerability in FortiWeb from Fortinet, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected FortiWeb versions: 8.0.0 through 8.0.3; 7.6.0 through 7.6.6; 7.4.0 through 7.4.11. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on January 27, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of FortiWeb you run against the affected versions below, and install the vendor's latest release.
- CISA's 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.
- Read the advisory on fortiguard.fortinet.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fortinet | FortiWeb | 8.0.0 through 8.0.3; 7.6.0 through 7.6.6; 7.4.0 through 7.4.11 | Not stated |
| Fortinet | FortiNAC-F | 7.6.3 through 7.6.5 | Not stated |
| Fortinet | FortiOS | 7.6.0 through 7.6.5; 7.4.0 through 7.4.10; 7.2.0 through 7.2.12; 7.0.0 through 7.0.18 | Not stated |
| Fortinet | FortiAnalyzer | 7.6.0 through 7.6.5; 7.4.0 through 7.4.9; 7.2.0 through 7.2.11; 7.0.0 through 7.0.15 | Not stated |
| Fortinet | FortiProxy | 7.6.0 through 7.6.4; 7.4.0 through 7.4.12; 7.2.0 through 7.2.15; 7.0.0 through 7.0.22 | Not stated |
| Fortinet | FortiManager | 7.6.0 through 7.6.5; 7.4.0 through 7.4.9; 7.2.0 through 7.2.11; 7.0.0 through 7.0.15 | Not stated |
| Siemens | RUGGEDCOM APE1808 | all versions | Not stated |
| Siemens | Ruggedcom Ape1808 Firmware | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (fortinet.com).
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How developers prevent this class of flaw
- Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
More Authentication Bypass Using an Alternate Path or Channel vulnerabilities (CWE-288)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- cert-portal.siemens.com/productcert/html/ssa-975644.htmlThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24858US Government Resource
Other vulnerabilities in FortiWeb
- 9.8 Critical severity
- 7.2 High severity
- 8.1 High severity
- 7.2 High severity
- 7.5 High severity
- 8.1 High severity
Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
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