Fortinet FortiCloud SSO Authentication Bypass Vulnerabilities
Fortinet disclosed two critical authentication bypass vulnerabilities, CVE-2025-59718 and CVE-2025-59719, affecting multiple products including FortiOS, FortiWeb, FortiProxy, and FortiSwitchManager. These flaws allow unauthenticated attackers to bypass FortiCloud SSO login authentication by sending crafted SAML messages if the FortiCloud SSO feature is enabled. The vulnerabilities are not exploitable by default, but become active when devices are registered to FortiCare with administrative SSO enabled, increasing the risk for organizations that have enabled this feature.
No exploitation in the wild or public proof-of-concept code has been reported as of the latest advisories, but security experts warn that threat actors are likely to target these vulnerabilities for initial access in the future. Fortinet and security researchers strongly recommend immediate upgrades to the latest fixed versions for all affected products to mitigate the risk. Detailed version guidance and mitigation steps have been provided to ensure organizations can secure their environments against potential attacks leveraging these flaws.
Timeline
Dec 10, 2025
SecurityOnline reports critical Fortinet SSO/SAML admin bypass flaw
A SecurityOnline report described a critical Fortinet vulnerability that could allow unauthenticated administrative bypass through FortiCloud SSO SAML forgery. No additional disclosure, patch, or victim-impact details are provided in the reference.
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