# CVE-2026-39808 — Fortinet FortiSandbox **CISA KEV** > As of 2026-07-17, CVE-2026-39808 is a CRITICAL-severity vulnerability in Fortinet FortiSandbox, CVSS v3.1 9.1, EPSS 47.3% (98.8th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-07-16), with a US federal remediation deadline of 2026-07-19. Threadlinqs Intelligence links 6 tracked threat campaigns to CVE-2026-39808, most recently “Critical FortiSandbox GUI Authentication Bypass (CVE-2026-107656)”. **Last updated:** 2026-07-17 ## What is CVE-2026-39808? A improper neutralization of special elements used in an os command ('os command injection') vulnerability in Fortinet FortiSandbox 4.4.0 through 4.4.8 may allow attacker to execute unauthorized code or commands via The record classifies CVE-2026-39808 under weakness class [CWE-78](https://intel.threadlinqs.com/cwe/CWE-78). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 183 days ago. ## Severity and exploitation probability - **CVSS v3.1 base score:** 9.1 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C`) - **EPSS (FIRST):** 47.3% probability of exploitation in the next 30 days, higher than 98.8% of all scored CVEs - **CISA KEV:** Listed since 2026-07-16, federal remediation deadline 2026-07-19 - **Threadlinqs priority:** 9/10 — CISA KEV-listed, which Threadlinqs floors at 9 - **Published:** 2026-04-14, last modified 2026-07-17 ## Is CVE-2026-39808 being exploited? CISA added CVE-2026-39808 to the Known Exploited Vulnerabilities catalog on 2026-07-16, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-07-19 under BOD 22-01. Weaponised exploit code for CVE-2026-39808 is publicly available. 7 public proof-of-concept repositories are tracked for this identifier. A ProjectDiscovery Nuclei detection template exists (`http/cves/2026/CVE-2026-39808.yaml`). It currently carries a trending score of 60 in the Threadlinqs vulnerability feed. - [ynsmroztas/FortiSandbox-RCE-Exploit-CVE-2026-39808](https://github.com/ynsmroztas/FortiSandbox-RCE-Exploit-CVE-2026-39808) (github) - [samu-delucas/CVE-2026-39808](https://github.com/samu-delucas/CVE-2026-39808) (github) - [0xBlackash/CVE-2026-39808](https://github.com/0xBlackash/CVE-2026-39808) (github) - [gotr00t0day/CVE-2026-39808](https://github.com/gotr00t0day/CVE-2026-39808) (github) - [HORKimhab/CVE-2026-39808](https://github.com/HORKimhab/CVE-2026-39808) (github) - [error-inside/CVE-2026-39808](https://github.com/error-inside/CVE-2026-39808) (github) - [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-39808.md) (trickest) ## Affected products and versions - [Fortinet](https://intel.threadlinqs.com/vendors/fortinet): FortiSandbox, FortiSandbox PaaS ## How to fix CVE-2026-39808 Because CVE-2026-39808 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-07-19. No vendor patch reference has been recorded for CVE-2026-39808 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise. ## Threat activity tracking CVE-2026-39808 6 tracked threats in the Threadlinqs corpus reference CVE-2026-39808, either in the campaign’s CVE list or as an indicator on the campaign record. - [Critical FortiSandbox GUI Authentication Bypass (CVE-2026-107656)](https://intel.threadlinqs.com/threat/TL-2026-3433) — CRITICAL · 2026-10-13 - [CISA KEV: Fortinet FortiSandbox OS Command Injection Vulnerabilities Exploited (CVE-2026-39808, CVE-2026-25089)](https://intel.threadlinqs.com/threat/TL-2026-1432) — CRITICAL · 2026-07-17 - [CISA Orders Federal Agencies to Patch Exploited Fortinet FortiSandbox Command Injection Flaws (CVE-2026-39808, CVE-2026-25089, CVE-2026-39813)](https://intel.threadlinqs.com/threat/TL-2026-1433) — CRITICAL · 2026-07-17 - [CISA Orders Patch of Actively Exploited Critical FortiSandbox OS Command Injection Flaws (CVE-2026-39808, CVE-2026-25089, CVE-2026-39813)](https://intel.threadlinqs.com/threat/TL-2026-1447) — CRITICAL · 2026-07-17 - [FortiSandbox VNC Server Exposure Allows Unauthenticated Access to Scanning VMs (CVE-2026-59835)](https://intel.threadlinqs.com/threat/TL-2026-1319) — HIGH · 2026-07-14 - [FortiSandbox Unauthenticated RCE Chain: JRPC API Path-Traversal Auth Bypass and OS Command Injection (CVE-2026-39813, CVE-2026-39808, CVE-2026-25089)](https://intel.threadlinqs.com/threat/TL-2026-0823) — CRITICAL · 2026-06-16 ## Sources Enriched from CVE.org, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories, ProjectDiscovery Nuclei. Last verified by Threadlinqs on 2026-10-10. **Other references** - [fortiguard.fortinet.com](https://fortiguard.fortinet.com/psirt/FG-IR-26-100) Canonical: https://intel.threadlinqs.com/cve/CVE-2026-39808 Full detection coverage and IOCs for threats exploiting CVE-2026-39808 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp