CVE-2026-121528

Published Nov 11, 2026 CVSS 3.1 · 7.7 High EPSS < 1% KEV · Not listed

Description

A improper certificate validation vulnerability in Fortinet FortiOS 7.6.0 through 7.6.4, FortiOS 7.4.0 through 7.4.9, FortiOS 7.2.0 through 7.2.13 may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the SSLVPN web portal and the backend destination website.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Fortinet

FortiOS

unaffected

Version	Status	Constraints
`7.6.0`	affected	≤ 7.6.4
`7.4.0`	affected	≤ 7.4.9
`7.2.0`	affected	≤ 7.2.13
`7.0.0`	affected	≤ 7.0.19
`6.4.0`	affected	≤ 6.4.16

No data.

Vendor Product Versions

Fortinet

Fortios

Version	Status	Scheme	Platform
`[7.6.0,7.6.4]`	affected	semver	—
`[7.4.0,7.4.9]`	affected	semver	—
`[7.2.0,7.2.13]`	affected	semver	—
`[7.0.0,7.0.19]`	affected	semver	—
`[6.4.0,6.4.16]`	affected	semver	—

Remediation

Vendor Solution

Upgrade to FortiOS version 8.0.0 or above Upgrade to FortiOS version 7.6.5 or above Upgrade to FortiOS version 7.4.10 or above Upgrade to FortiOS version 7.2.14 or above

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.243% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://fortiguard.fortinet.com/psirt/FG-IR-26-193

History

Nov 13, 2026 11:15 AM Title updated View changes

Type	Values Removed	Values Added
Title	SSLVPN Certificate Validation Bypass Enables Man‑in‑the‑Middle Attacks

Nov 12, 2026 1:30 PM Title updated View changes

Type	Values Removed	Values Added
Title		SSLVPN Certificate Validation Bypass Enables Man‑in‑the‑Middle Attacks

Nov 11, 2026 9:45 PM Description updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		A improper certificate validation vulnerability in Fortinet FortiOS 7.6.0 through 7.6.4, FortiOS 7.4.0 through 7.4.9, FortiOS 7.2.0 through 7.2.13 may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the SSLVPN web portal and the backend destination website.
First Time appeared		Fortinet Fortinet fortios
Weaknesses		CWE-295
CPEs		cpe:2.3:o:fortinet:fortios:6.4.0:::::::* cpe:2.3:o:fortinet:fortios:6.4.10:::::::* cpe:2.3:o:fortinet:fortios:6.4.11:::::::* cpe:2.3:o:fortinet:fortios:6.4.12:::::::* cpe:2.3:o:fortinet:fortios:6.4.13:::::::* cpe:2.3:o:fortinet:fortios:6.4.14:::::::* cpe:2.3:o:fortinet:fortios:6.4.15:::::::* cpe:2.3:o:fortinet:fortios:6.4.16:::::::* cpe:2.3:o:fortinet:fortios:6.4.1:::::::* cpe:2.3:o:fortinet:fortios:6.4.2:::::::* cpe:2.3:o:fortinet:fortios:6.4.3:::::::* cpe:2.3:o:fortinet:fortios:6.4.4:::::::* cpe:2.3:o:fortinet:fortios:6.4.5:::::::* cpe:2.3:o:fortinet:fortios:6.4.6:::::::* cpe:2.3:o:fortinet:fortios:6.4.7:::::::* cpe:2.3:o:fortinet:fortios:6.4.8:::::::* cpe:2.3:o:fortinet:fortios:6.4.9:::::::* cpe:2.3:o:fortinet:fortios:7.0.0:::::::* cpe:2.3:o:fortinet:fortios:7.0.10:::::::* cpe:2.3:o:fortinet:fortios:7.0.11:::::::* cpe:2.3:o:fortinet:fortios:7.0.12:::::::* cpe:2.3:o:fortinet:fortios:7.0.13:::::::* cpe:2.3:o:fortinet:fortios:7.0.14:::::::* cpe:2.3:o:fortinet:fortios:7.0.15:::::::* cpe:2.3:o:fortinet:fortios:7.0.16:::::::* cpe:2.3:o:fortinet:fortios:7.0.17:::::::* cpe:2.3:o:fortinet:fortios:7.0.18:::::::* cpe:2.3:o:fortinet:fortios:7.0.19:::::::* cpe:2.3:o:fortinet:fortios:7.0.1:::::::* cpe:2.3:o:fortinet:fortios:7.0.2:::::::* cpe:2.3:o:fortinet:fortios:7.0.3:::::::* cpe:2.3:o:fortinet:fortios:7.0.4:::::::* cpe:2.3:o:fortinet:fortios:7.0.5:::::::* cpe:2.3:o:fortinet:fortios:7.0.6:::::::* cpe:2.3:o:fortinet:fortios:7.0.7:::::::* cpe:2.3:o:fortinet:fortios:7.0.8:::::::* cpe:2.3:o:fortinet:fortios:7.0.9:::::::* cpe:2.3:o:fortinet:fortios:7.2.0:::::::* cpe:2.3:o:fortinet:fortios:7.2.10:::::::* cpe:2.3:o:fortinet:fortios:7.2.11:::::::* cpe:2.3:o:fortinet:fortios:7.2.12:::::::* cpe:2.3:o:fortinet:fortios:7.2.13:::::::* cpe:2.3:o:fortinet:fortios:7.2.1:::::::* cpe:2.3:o:fortinet:fortios:7.2.2:::::::* cpe:2.3:o:fortinet:fortios:7.2.3:::::::* cpe:2.3:o:fortinet:fortios:7.2.4:::::::* cpe:2.3:o:fortinet:fortios:7.2.5:::::::* cpe:2.3:o:fortinet:fortios:7.2.6:::::::* cpe:2.3:o:fortinet:fortios:7.2.7:::::::* cpe:2.3:o:fortinet:fortios:7.2.8:::::::* cpe:2.3:o:fortinet:fortios:7.2.9:::::::* cpe:2.3:o:fortinet:fortios:7.4.0:::::::* cpe:2.3:o:fortinet:fortios:7.4.1:::::::* cpe:2.3:o:fortinet:fortios:7.4.2:::::::* cpe:2.3:o:fortinet:fortios:7.4.3:::::::* cpe:2.3:o:fortinet:fortios:7.4.4:::::::* cpe:2.3:o:fortinet:fortios:7.4.5:::::::* cpe:2.3:o:fortinet:fortios:7.4.6:::::::* cpe:2.3:o:fortinet:fortios:7.4.7:::::::* cpe:2.3:o:fortinet:fortios:7.4.8:::::::* cpe:2.3:o:fortinet:fortios:7.4.9:::::::* cpe:2.3:o:fortinet:fortios:7.6.0:::::::* cpe:2.3:o:fortinet:fortios:7.6.1:::::::* cpe:2.3:o:fortinet:fortios:7.6.2:::::::* cpe:2.3:o:fortinet:fortios:7.6.3:::::::* cpe:2.3:o:fortinet:fortios:7.6.4:::::::*
Vendors & Products		Fortinet Fortinet fortios
References		https://fortiguard.fortinet.com/psirt/FG-IR-26-193
Metrics		cvssV3_1 `{'score': 7.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C'}`