FortiWeb: Improper Authentication
CVE-2026-26035 is a critical-severity improper authentication 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 8.0.2; 7.6.0 through 7.6.6; 7.4.0 through 7.4.11, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.75% chance of exploitation within 30 days, higher than 56% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of FortiWeb you run against the affected versions below, and install the vendor's latest release.
- 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 8.0.2; 7.6.0 through 7.6.6; 7.4.0 through 7.4.11; 7.2.0 through 7.2.12; 7.0.0 through 7.0.12 | 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 Improper Authentication vulnerability [CWE-287] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.2, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11, FortiWeb 7.2.0 through 7.2.12, FortiWeb 7.0.0 through 7.0.12 may allow a remote unauthenticated attacker to login into the Fortiweb GUI/CLI with a random username and password
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How developers prevent this class of flaw
- Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in FortiWeb
- 7.2 High severity
- 8.1 High severity
- 7.2 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.1 High severity
Recent Improper Authentication vulnerabilities
- 9.1 Critical severity
- 8.1 High severity
- 7.4 High severity
- 7.5 High severity
- 9.4 Critical severity
- 8.1 High severity
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