CVE-2026-84393: improper validation of certificate with host mismatch vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6, FortiProxy 7.6.2 through 7.6.6 may allow attacker to information disclosure via
CVE-2026-84393 key facts
- CISA KEV
- Not listed (catalogue checked )
- Highest advisory rating
- High
- CVSS base score
- 8.1 (Fortinet), 8.1 (Fortinet)
- CVSS 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· base score 7.3, scored by fortinetAttack vector: network. Attack complexity: high. Privileges required: none. User interaction: none. Scope: unchanged. Confidentiality impact: high. Integrity impact: high. Availability impact: high.- Weakness
- CWE-297 Information disclosure
- EPSS
- 0.28% chance of exploitation in the next 30 days (20th percentile). FIRST EPSS, .
- CISA SSVC
- Exploitation: none observed. Automatable: no. Technical impact: total. CISA, .
- Vendor advisories
- 2 from Fortinet
- Assigned by
- fortinet (CNA)
- CVE record published
- Listed by VulniPulse
Ratings, versions and fixes are quoted from the vendor advisories that cover only CVE-2026-84393; each belongs to its advisory, not to every product listed. How records are collected and checked.
Description
A improper validation of certificate with host mismatch vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6, FortiProxy 7.6.2 through 7.6.6 may allow attacker to information disclosure via <insert attack vector here>
Text from the CVE.org record (fortinet).
How do I fix CVE-2026-84393?
- Upgrade to FortiOS version 8.0.0 or above Upgrade to FortiOS version 7.6.7 or above Upgrade to upcoming FortiProxy version 8.0.0 or above Upgrade to upcoming FortiProxy version 7.6.7 or above Fortinet remediated this issue in FortiSASE version 26.2.2 (not released) and hence customers do not need to perform any action. (CVE.org record)
Vendor advisories for CVE-2026-84393
Fortinet
2 advisories- Advisory severityHigh8.1
High [CVE-2026-84393] improper validation of certificate with host mismatch vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6, FortiProxy 7.6.2 through 7.6.6 may allow attacker to information disclosure via <insert attack vector here>
CVE-2026-84393Source published Source updated
A improper validation of certificate with host mismatch vulnerability in Fortinet FortiOS 7.6.1 through 7.6.6, FortiProxy 7.6.2 through 7.6.6 may allow attacker to information disclosure
- Affected products in this advisory
- FortiOS
- FortiProxy
- Source-reported affected versions
- FortiOS FortiOS: 7.2 through 8.0 (vendor-listed versions)
- FortiProxy FortiProxy: 7.2 through 8.0 (vendor-listed versions)
- Source-reported fixed versions
- No fixed-version detail extracted. This does not mean no fix exists.
- Mitigation guidance
- No mitigation guidance extracted; consult the source.
- Advisory severityHigh8.1
High [CVE-2026-84393] ZTNA Portal Improper Certificate Validation
FG-IR-26-174Source published Source updated
CVSSv3 Score: 8.1 An improper certificate validation vulnerability [CWE-295] in FortiOS and FortiProxy Agentless ZTNA portal may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the ZTNA portal and the backend destination website. Revised on 2026-09-08 00:00:00
- Affected products in this advisory
- FortiOS
- FortiProxy
- Source-reported affected versions
- FortiOS FortiOS: 7.2 through 8.0 (vendor-listed versions)
- FortiProxy FortiProxy: 7.2 through 8.0 (vendor-listed versions)
- Source-reported fixed versions
- No fixed-version detail extracted. This does not mean no fix exists.
- Mitigation guidance
- No mitigation guidance extracted; consult the source.
References
Timeline
- CVE record published
- First vendor advisory listed by VulniPulse
- CVE record last updated
More Fortinet advisories
CVE-2026-106175Oct 13, 2026Double free in signal handlerCVE-2025-61624Apr 14, 2026Path Traversal in CLICVE-2026-24858Jan 27, 2026FortiOS: Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288]CVE-2025-59718Dec 9, 2025improper verification of cryptographic signature vulnerability in Fortinet FortiOS 7.6.0CVE-2025-59719Dec 9, 2025FortiOS: improper verification of cryptographic signature vulnerability in FortinetCVE-2024-47569Oct 14, 2025insertion of sensitive information into sent data vulnerability in Fortinet FortiMail
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