U.S. CISA adds Fortinet FortiSandbox and Microsoft SharePoint flaws to its Known Exploited Vulnerabilities catalog

CVE-2026-25089 is an OS command injection flaw (CWE-78) in Fortinet FortiSandbox caused by improper neutralization of special elements in OS commands, allowing an unauthenticated attacker to execute unauthorized commands by sending specifically crafted HTTP requests to the product. The flaw is network-exploitable with no privileges or user interaction required (CVSS 3.1 score of 9.8), meaning any reachable instance — hardware/VM appliance, FortiSandbox Cloud, or FortiSandbox PaaS — is exposed to system-level command execution. Successful exploitation carries high impact to confidentiality, integrity, and availability on the sandbox itself and can serve as a foothold into the surrounding network. Organizations running FortiSandbox 5.0.0–5.0.5, 4.4.0–4.4.8, or 4.2 (all versions), as well as FortiSandbox Cloud 5.0.4–5.0.5 and FortiSandbox PaaS 5.0.4–5.0.5, are affected. The vulnerability is being actively exploited in the wild: CISA added it to the KEV catalog on 2026-07-16, EPSS assigns a 76.1% probability of exploitation within 30 days (100th percentile), and news coverage describes FortiSandbox bugs under active attack, though no public proof-of-concept is known.

Do: Upgrade FortiSandbox to a release beyond the affected ranges — newer than 5.0.5, 4.4.8, and 4.2 — and update FortiSandbox Cloud and PaaS beyond 5.0.5, following Fortinet's PSIRT advisory for the exact fixed versions (not specified in this data). Until patched, restrict the FortiSandbox management interface from direct internet exposure and review appliance logs for signs of command-injection exploitation. Organizations subject to CISA's KEV requirements must apply vendor mitigations per BOD 26-04 timelines or discontinue cloud use of the product if mitigations are unavailable.

CVE-2026-39808 is an OS command injection flaw (CWE-78) in Fortinet FortiSandbox versions 4.4.0 through 4.4.8, caused by improper neutralization of special elements passed to OS commands. The vulnerability is network-reachable, requires no privileges or user interaction (CVSS 3.1: 9.8, AV:N/AC:L/PR:N/UI:N), though CISA's description does not specify the exact entry point that a remote unauthenticated attacker abuses to trigger it. Successful exploitation lets the attacker execute unauthorized code or commands on the appliance, with high impact to confidentiality, integrity, and availability. Any organization running FortiSandbox 4.4.0-4.4.8 is affected; these sandboxing appliances are typically deployed as add-ons to enterprise FortiGate security estates. The flaw was added to CISA's KEV on 2026-07-16, and press coverage describes critical FortiSandbox bugs coming under active attack, so in-the-wild exploitation should be assumed.

Do: Upgrade all FortiSandbox appliances out of the affected 4.4.0-4.4.8 range to a fixed release per Fortinet's advisory, prioritizing internet-exposed units and complying with the CISA KEV required action (added 2026-07-16) and BOD 26-04 guidance. Until patched, restrict network access to the appliance's management and analysis interfaces and triage for signs of command execution such as unexpected processes or outbound connections. Confirm the specific fixed 4.4.x build in Fortinet's PSIRT advisory before scheduling upgrades.

CVE-2026-58644 is a critical (CVSS 9.8) deserialization-of-untrusted-data flaw (CWE-502) in Microsoft SharePoint Server that allows an unauthorized attacker to execute code over a network. An attacker triggers it by sending crafted serialized data to the server, with no privileges or user interaction required, gaining code execution in the context of the SharePoint service. Any organization running on-premises SharePoint Server is affected, with highest risk for instances reachable from the internet or by untrusted network users. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-07-16, and contemporaneous headlines describe an exploited SharePoint zero-day, indicating active in-the-wild exploitation; EPSS assigns a roughly 16% probability of exploitation within 30 days (97th percentile). Fixes shipped in Microsoft's July 2026 Patch Tuesday release (621 CVEs total), while no public proof-of-concept for this specific CVE is documented.

Do: Apply Microsoft's July 2026 Patch Tuesday security updates for SharePoint Server immediately, prioritizing internet-facing instances, as required for federal agencies under CISA BOD 26-04 and the KEV listing. If patching must be delayed, restrict network exposure to SharePoint per Microsoft/CISA mitigation guidance and assess each asset's internet exposure. Review SharePoint and web-server logs for signs of exploitation and enumerate all SharePoint Server installations in the environment to confirm coverage.