FortiMail: Authorization Bypass Through User-Controlled Key
CVE-2026-126152 is a high-severity authorization bypass through user-controlled key vulnerability in FortiMail from Fortinet, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. Affected FortiMail versions: 8.0.0 through 8.0.1; 7.6.0 through 7.6.6; 7.4.0 through 7.4.8, 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 0.6% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of FortiMail 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fortinet | FortiMail | 8.0.0 through 8.0.1; 7.6.0 through 7.6.6; 7.4.0 through 7.4.8; 7.2.0 through 7.2.9; 7.0.0 through 7.0.9 | 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
- HighAdministrator-level access is required first.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L. Scored by CNA (fortinet.com).
Official description
A authorization bypass through user-controlled key vulnerability in Fortinet FortiMail 8.0.0 through 8.0.1, FortiMail 7.6.0 through 7.6.6, FortiMail 7.4.0 through 7.4.8, FortiMail 7.2 all versions may allow an authenticated remote attacker to delete arbitrary directories as root, or to access or delete other users' calendar and mailbox data across tenant domains, via crafted HTTP requests to the webmail and administrative interfaces.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How developers prevent this class of flaw
- For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
More Authorization Bypass Through User-Controlled Key vulnerabilities (CWE-639)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in FortiMail
- 9.8 Critical severity
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
- 7.5 High severity
Recent Authorization Bypass Through User-Controlled Key vulnerabilities
- 9.1 Critical severity
- 8.2 High severity
- 8.7 High severity
- 7.5 High severity
- 9.1 Critical severity
- 8.8 High severity
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