CVE-2026-25089 — Fortinet FortiSandbox: unauthenticated OS command injection in the web UI's VNC-launch handler (CVSS 9.8)

Fortinet patched CVE-2026-25089 (CWE-78, internal reference FG-IR-26-141) on 9 June: the FortiSandbox web interface's "start VNC" handler passes attacker-controlled JSON to the underlying OS without sanitisation, allowing a remote unauthenticated attacker to achieve second-order command injection via a crafted HTTP request (NCSC-NL, 2026-06-11). Affected: FortiSandbox 5.0.0–5.0.5 and 4.4.0–4.4.8 (plus corresponding Cloud/PaaS builds); fixed in 5.0.6 and 4.4.9. CCB Belgium urges immediate patching and warns that the public availability of a proof-of-concept exploit increases the likelihood of exploitation (CCB Belgium, 2026-06-11). No in-the-wild exploitation is reported, and the management interface is not meant to be internet-reachable — but with a public PoC available, a compromised FortiSandbox hands an attacker every file your SOC submits for detonation, plus a trusted foothold inside the security stack (T1190). Discovered internally by Fortinet's product-security team; the FortiGuard PSIRT page was unreachable in this run (see § 7).

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