Fortinet Firewalls Targeted as Attackers Bypass Patch for Critical FortiGate Flaw

 

Critical vulnerabilities in FortiGate systems continue to be exploited, even after fixes were deployed, users now confirm. Though updates arrived aiming to correct the problem labeled CVE-2025-59718, they appear incomplete. Authentication safeguards can still be sidestepped by threat actors taking advantage of the gap. This suggests earlier remedies failed to close every loophole tied to the flaw. Confidence in the patch process is weakening as real-world attacks persist. 

Several admins report breaches on FortiGate units using FortiOS 7.4.9, along with systems updated to 7.4.10. While Fortinet claimed a fix arrived in December via version 7.4.9 - tied to CVE-2025-59718 - one user states internal confirmation showed the flaw persisted past that patch. Updates such as 7.4.11, 7.6.6, and 8.0.0 are said to be underway, aiming complete resolution. 

One case involved an administrator spotting a suspicious single sign-on attempt on a FortiGate system with FortiOS version 7.4.9. A security alert appeared after detection of a freshly added local admin profile, behavior seen before during prior attacks exploiting this flaw. Activity records indicated the new account emerged right after an SSO entry tied to the email cloud-init@mail.io. That access came from the IP 104.28.244.114, marking another point in the timeline. 

A few others using Fortinet noticed very similar incidents. Their firewall - running version 7.4.9 of FortiOS - logged an identical email and source IP during access attempts, followed by the addition of a privileged profile labeled “helpdesk.” Confirmation came afterward from Fortinet’s development group: the security flaw remained active even after update 7.4.10. 

Unexpectedly, the behavior aligns with earlier observations from Arctic Wolf, a cybersecurity company. In late 2025, they identified exploitation of vulnerability CVE-2025-59718 through manipulated SAML data. Instead of standard procedures, hackers leveraged flaws in FortiGate's FortiCloud login mechanism. Through this weakness, unauthorized users gained access to privileged administrator credentials. 

Nowhere in recent updates does Fortinet address the newest claims of system breaches, even after repeated outreach attempts. Without a complete fix available just yet, experts suggest pausing certain functions as a stopgap solution. Turning off the FortiCloud SSO capability stands out - especially when active - since attacks largely flow through that pathway. Earlier warnings from Fortinet pointed out that FortiCloud SSO stays inactive unless tied to a FortiCare registration - this setup naturally reduces exposure. 

Despite that, findings shared by Shadowserver in mid-December revealed over 25,000 such devices already running the feature publicly. Though efforts have protected most of them, around 11,000 still appear accessible across the web. Their security status remains uncertain. 

Faced with unpatched FortiOS versions, admins might consider revising login configurations while Fortinet works on fixes. Some could turn off unused single sign-on options as a precaution. Watching system records carefully may help spot odd behavior tied to admin access during this period.