CVE-2026-25089, Fortinet FortiSandbox: unauthenticated OS command injection in the web UI's VNC-launch handler (CVSS 9.8)
Defender actions
- Patch FortiSandbox to 5.0.6 / 4.4.9 and confirm the management interface is off the internet (CVE-2026-25089). A compromised sandbox exposes every file your SOC detonates.
- Patch all three FortiSandbox CVEs and restrict the management interface (§ 4). CVE-2026-39808/39813 (April patches) and CVE-2026-25089 (06-09 patch) are under simultaneous exploitation; a compromised sandbox suppresses blocking across the FortiGate/FortiMail stack. Watch JRPC/web-UI access logs for unauthenticated external POSTs.
Analysis
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 (.
CVE Summary Table
| CVE | Product | CVSS | EPSS | KEV | Exploited | Patch | Source |
|---|---|---|---|---|---|---|---|
| CVE-2026-35273 | Oracle PeopleSoft PeopleTools 8.61/8.62 (PSEMHUB) | 9.8 | n/a | No | Yes, zero-day, UNC6240 | Out-of-band alert 2026-06-10 | Oracle |
| CVE-2026-49261 | MariaDB Server (Galera wsrep_notify_cmd) |
10.0 | n/a | No | No | 11.8.8 / 11.4.12 / 10.11.18 / 10.6.27 | NCSC-CH |
| CVE-2026-45657 | Windows kernel (TCP/IP) | 9.8 | n/a | No | No | June 2026 cumulative | MSRC |
| CVE-2026-26142 | Nuance PowerScribe | 9.8 | n/a | No | No | June 2026 update | MSRC |
| CVE-2026-47643 | Azure Stack Edge | 9.8 | n/a | No | No | June 2026 update | MSRC |
| CVE-2026-48579 | Exchange Online | 9.1 | n/a | No | No | Service-side, no customer action | MSRC |
| CVE-2026-25089 | Fortinet FortiSandbox | 9.8 | n/a | No | PoC public | 5.0.6 / 4.4.9 | NCSC-NL |
Cited evidence
UPDATE (originally covered 2026-06-12): When CVE-2026-25089 was covered on 06-12 it was disclosure-only.
Updates1
When CVE-2026-25089 was covered on 06-12 it was disclosure-only. Threat-intel firm Defused Cyber has now reported active exploitation of three FortiSandbox flaws within a single 24-hour window, CVE-2026-39808 (CVSS 9.8, JRPC OS command injection), CVE-2026-39813 (CVSS 9.1, JRPC path traversal / auth bypass), both with patches available since April 2026, and CVE-2026-25089 (CVSS 9.8, web-UI command injection), patched 2026-06-09 (Security Affairs, 2026-06-16).
FortiSandbox supplies sandboxed file verdicts that FortiGate, FortiMail, FortiProxy and FortiClient consume to make blocking decisions, so a compromised sandbox can suppress detection across the dependent Fortinet stack (Help Net Security, 2026-06-16). The CVE-2026-25089 exploit seen in the wild appears AI-generated and is assessed as faulty, yet still finds traction against unpatched deployments, evidence that exposed, unpatched FortiSandbox interfaces remain. Fortinet has not yet officially confirmed exploitation. Patch all three; until then, restrict management-interface exposure and watch FortiSandbox web-UI/JRPC access logs for unauthenticated external POSTs.
Sources4
Revision history
- Published 2026-06-12-5ab9a319
- Update 2026-06-17-e102009c
Three critical FortiSandbox flaws are now under simultaneous active exploitation, CVE-2026-39808, CVE-2026-39813 (April patches) and CVE-2026-25089 (patched 2026-06-09, previously disclosure-only here on 06-12) were all observed exploited in a 24-hour window; FortiSandbox feeds verdicts to the wider FortiGate/FortiMail stack (§ 4).
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