Fortinet warns of active FortiCloud SSO bypass affecting updated devices
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2025-59718 | Critical FortiCloud SSO Authentication Bypass in Fortinet FortiOS and FortiProxy CVE-2025-59718 is a critical (CVSS 9.8) improper verification of cryptographic signature flaw (CWE-347) in the FortiCloud SSO login flow of Fortinet FortiOS, FortiProxy, and FortiSwitchManager, with the Siemens RUGGEDCOM APE1808 appliance also listed in the CVE's affected CPE entries. An unauthenticated attacker who can reach a device's FortiCloud SSO login can submit a crafted SAML response message whose cryptographic signature is not properly verified, bypassing authentication entirely. The bypass grants unauthorized access to the affected device with high impact on confidentiality, integrity, and availability, typically administrative control of the management interface. Any organization running the affected FortiOS 7.0–7.6, FortiProxy 7.0–7.6, or FortiSwitchManager 7.0–7.2 versions that uses FortiCloud SSO for administrative login is exposed. Exploitation is confirmed in the wild: the flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-12-16, security reporting describes active attacks against FortiGate firewalls via this SAML SSO bypass, and EPSS assigns a 68.3% probability of exploitation within 30 days. Do: Upgrade all affected products out of the vulnerable ranges — FortiOS beyond 7.6.3/7.4.8/7.2.11/7.0.17, FortiProxy beyond 7.6.3/7.4.10/7.2.14/7.0.21, and FortiSwitchManager beyond 7.2.6/7.0.5 — using the fixed builds listed in Fortinet's security advisory, and patch Siemens RUGGEDCOM APE1808 firmware per Siemens guidance. As interim mitigation, disable or restrict FortiCloud SSO-based administrative login, limit management-interface exposure to trusted networks, and review admin/SSO logs for anomalous sign-ins or forged SAML responses. Given the KEV listing, US federal agencies must apply vendor mitigations or discontinue use of affected products per BOD 22-01. | 9.8 | 68% | KEV |
| masslikely on the order of 100,000+ internet-exposed FortiOS/FortiProxy systems (Fortinet's deployed base is in the millions); the directly exploitable set is the… | |
| CVE-2025-59719 | Unauthenticated SAML Signature Bypass in Fortinet FortiWeb (FortiCloud SSO) FortiWeb contains an improper verification of cryptographic signature (CWE-347) in its FortiCloud SSO login flow, allowing an unauthenticated attacker to bypass authentication by submitting a crafted SAML response whose signature is not properly validated. Because this requires no privileges or user interaction and is network-reachable, successful exploitation grants the attacker the access of a legitimate SSO-authenticated administrator to the appliance's management interface. The flaw affects FortiWeb 8.0.0, 7.6.0 through 7.6.4, and 7.4.0 through 7.4.9. Organizations running these versions are affected, particularly where the management interface is reachable and FortiCloud SSO login is enabled. As of this analysis the flaw is not in the CISA KEV catalog and no public proof-of-concept is known, but a closely related SAML SSO authentication bypass in FortiGate firewalls (CVE-2025-59718) is under active attack and Fortinet has issued urgent authentication patches, so elevated exploitation risk is plausible. Do: Upgrade FortiWeb to a patched release per Fortinet's PSIRT advisory covering CVE-2025-59719, prioritizing internet-facing appliances on 8.0.0, 7.6.x, or 7.4.x. As interim mitigation, restrict access to the management interface, disable or limit FortiCloud SSO login in favor of local or hardened admin authentication, and review SSO login logs for successful authentications from unexpected sources. Note that the sibling FortiGate SAML bypass (CVE-2025-59718) is being actively exploited, so treat this patch as urgent. | 9.8 | 29% |
| largetens of thousands of internet-exposed FortiWeb appliances (order of magnitude ~10k-100k), with the exploitable subset limited to deployments using FortiCloud… |
Full article551 words · extracted from securityaffairs.com · click to collapse
Fortinet confirmed attacks are bypassing FortiCloud SSO authentication, affecting even fully patched devices, similar to recent SSO flaws.
Fortinet confirmed attacks bypass FortiCloud SSO on fully patched devices. Threat actors automate firewall changes, add users, enable VPNs, and steal configs, in campaigns resembling December 2025 exploits of critical FortiCloud SSO flaws.
Arctic Wolf researchers reported a new automated attack cluster observed since January 15, 2026, targeting FortiGate devices. Attackers created generic accounts for persistence, enabled VPN access, and exfiltrated firewall configurations. The activity resembles a December 2025 campaign involving admin SSO logins and config theft. Arctic Wolf has detections in place and is monitoring the evolving threat.
“Starting on January 15, 2026, Arctic Wolf began observing a new cluster of automated malicious activity involving unauthorized firewall configuration changes on FortiGate devices.” reads the report published by Arctic Wolf. “This activity involved the creation of generic accounts intended for persistence, configuration changes granting VPN access to those accounts, as well as exfiltration of firewall configurations. “
In December 2025, Fortinet disclosed two critical SSO authentication bypass flaws, tracked as CVE-2025-59718 and CVE-2025-59719, which are improper verification of cryptographic signature issues.
Threat actors started exploiting the two critical flaws in Fortinet products days after patch release, Arctic Wolf warned.
Arctic Wolf researchers observed attackers began exploiting critical Fortinet authentication bypass flaws on December 12, just three days after patches were issued. The attacks involved malicious SSO logins on FortiGate devices, mainly targeting admin accounts from multiple hosting providers. After gaining access, the attackers exported device configurations via the GUI. These files include hashed credentials, which threat actors can attempt to crack offline, increasing the risk of further compromise.
Recent intrusions show malicious SSO logins from a small set of hosting providers, often targeting the [email protected] account. After successful SSO access, attackers quickly exported firewall configurations via the GUI and created secondary admin accounts for persistence. These actions occurred within seconds, suggesting highly automated activity.
This week, Fortinet confirmed that attacks succeeded even against devices patched for CVE-2025-59718 and CVE-2025-59719.
The company identified a new attack path after observing login exploits on fully updated devices. A fix is in progress, an advisory is pending, and all SAML SSO implementations may be affected.
“Recently, a small number of customers reported unexpected login activity occurring on their devices, which appeared very similar to the previous issue. However, in the last 24 hours, we have identified a number of cases where the exploit was to a device that had been fully upgraded to the latest release at the time of the attack, which suggested a new attack path.” reads the advisory published by the company.
“Fortinet product security has identified the issue, and the company is working on a fix to remediate this occurrence. An advisory will be issued as the fix scope and timeline is available. It is important to note that while, at this time, only exploitation of FortiCloud SSO has been observed, this issue is applicable to all SAML SSO implementations.”
Fortinet is developing a fix, in the meantime, it released IOCs to aid threat hunting. Customers are urged to restrict admin access, limit it to local IPs, and temporarily disable FortiCloud SSO as a workaround.
Follow me on Twitter: @securityaffairs and Facebook and Mastodon
(SecurityAffairs – hacking, SSO)
Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/187250/security/fortinet-warns-of-active-forticloud-sso-bypass-affecting-updated-devices.html