CVE-2026-121530: improper authentication vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6 may allow a remote authenticated attacker to gain improper access control via an invalid token after entering a valid username and password
CVE-2026-121530 key facts
- CISA KEV
- Not listed (catalogue checked )
- Highest advisory rating
- Medium
- CVSS base score
- 5.9 (Fortinet), 5.9 (Fortinet)
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C· base score 5.9, scored by fortinetAttack vector: network. Attack complexity: high. Privileges required: high. User interaction: none. Scope: unchanged. Confidentiality impact: high. Integrity impact: high. Availability impact: high.- Weakness
- CWE-287 Improper access control
- 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-2026-121530; each belongs to its advisory, not to every product listed. How records are collected and checked.
Description
A improper authentication vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6 may allow a remote authenticated attacker to gain improper access control via an invalid token after entering a valid username and password
Text from the CVE.org record (fortinet).
How do I fix CVE-2026-121530?
- Upgrade to FortiOS version 8.0.0 or above Upgrade to FortiOS version 7.6.7 or above (CVE.org record)
Vendor advisories for CVE-2026-121530
Fortinet
2 advisories- Advisory severityMedium5.9
Medium [CVE-2026-121530] improper authentication vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6 may allow a remote authenticated attacker to gain improper access control via an invalid token after entering a valid username and password
CVE-2026-121530Source published Source updated
A improper authentication vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6 may allow a remote authenticated attacker to gain improper access control via an invalid token after entering a valid username and password
- Affected products in this advisory
- FortiOS
- Source-reported affected versions
- FortiOS: 7.6.0 through 7.6.6 (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 severityMedium5.9
Medium [CVE-2026-121530] Broken Access Control in Two-Factor-Authentication
FG-IR-26-195Source published Source updated
CVSSv3 Score: 5.9 An Improper Authentication vulnerability [CWE-287] in the FortiOS Remote Radius Type Admin Two-Factor (TFA) Authentication may allow a remote authenticated attacker with at least read-only permission to log in to the FortiOS GUI with an invalid token after entering a valid username and password, in scenarios where the RADIUS server returns an additional "Access-Challenge" response following an invalid TFA token. Revised on 2026-11-10 00:00:00
- Affected products in this advisory
- FortiOS
- Source-reported affected versions
- FortiOS: 7.6.0 through 7.6.6 (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
More Fortinet advisories
CVE-2026-126255Nov 10, 2026Improper neutralization of special elements in output used by a downstream componentCVE-2026-121530Nov 10, 2026Broken Access Control in Two-Factor-AuthenticationCVE-2026-126253Nov 10, 2026Authentication bypass by primary weaknessCVE-2026-106174Oct 13, 2026GUI Denial of ServiceCVE-2026-106175Oct 13, 2026Double free in signal handlerCVE-2025-53844May 12, 2026Out-of-bounds access in CAPWAP daemon
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