CVE-2026-24858

Deeper analysis

CVE-2026-24858 is an authentication bypass vulnerability (CWE-288) affecting multiple Fortinet products when FortiCloud SSO authentication is enabled. Impacted versions include FortiAnalyzer 7.0.0–7.0.15, 7.2.0–7.2.11, 7.4.0–7.4.9 and 7.6.0–7.6.5; FortiManager in the same ranges; FortiNAC-F 7.6.3–7.6.5; FortiOS 7.0.0–7.0.18, 7.2.0–7.2.12, 7.4.0–7.4.10 and 7.6.0–7.6.5; FortiProxy 7.0.0–7.0.22, 7.2.0–7.2.15, 7.4.0–7.4.12 and 7.6.0–7.6.4; and FortiWeb 7.4.0–7.4.11, 7.6.0–7.6.6 and 8.0.0–8.0.3. The flaw permits an attacker to authenticate to devices they do not own by leveraging an alternate path through FortiCloud SSO.

An attacker who possesses a valid FortiCloud account and at least one registered device can exploit the issue to obtain administrative access to other organizations’ devices that also have FortiCloud SSO enabled. Successful exploitation grants full control equivalent to a legitimate administrator, including the ability to read, modify or delete configuration and data on the affected appliances. The vulnerability carries a CVSS 3.1 score of 9.8.

Fortinet advisory FG-IR-26-060 and the associated analysis blog describe the root cause and recommend immediate upgrade to the fixed releases listed in the bulletin; organizations that cannot patch promptly are advised to disable FortiCloud SSO authentication. The issue also appears in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild.

EPSS for the CVE rose sharply from a low baseline to a peak of 0.1645 on 28 January 2026 before receding to the current value of 0.0480, indicating a clear post-disclosure increase in exploitation interest.