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CVE-2026-121528VulnerabilityPublished

Fortinet FortiOS · Improper Certificate Validation Vulnerability

Source GCVE Database

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Authoritative record:CVE-2026-121528· High 7.7

Public exploit available · CVSS 7.7 High · patch available : patch FortiOS as a priority.

Data as of 12 Nov 2026, 02:49 UTC

CVSS 3.1 base score
7.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (fortinet)CVSS 3.17.7
Patch
Available
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CVSS exploit maturity: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
FortinetFortiOSAffected
  • >=7.6.0 <=7.6.4
  • >=7.4.0 <=7.4.9
  • >=7.2.0 <=7.2.13
  • >=7.0.0 <=7.0.19
  • >=6.4.0 <=6.4.16
Fixed in–

AI-suggested

If you cannot patch yet, organizations should consider additional network protections such as monitoring for suspicious SSLVPN traffic and restricting access to trusted networks. Avoid relying solely on the SSLVPN web portal for sensitive communications until the vulnerability is addressed.

Description

An improper certificate validation vulnerability exists in Fortinet FortiOS versions 7.6.0 through 7.6.4, 7.4.0 through 7.4.9, and 7.2.0 through 7.2.13. This flaw may allow a remote, unauthenticated attacker to perform a Man-in-the-Middle (MitM) attack on the SSLVPN web portal's communication with backend destination websites.

References

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