Fortinet security advisory (AV26-351) – Update 2
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Serial number: AV26-351 Date: April 14, 2026 Updated: July 16, 2026 On April 14, 2026, Fortinet published security advisories to address vulnerabilities in multiple products. Included were critical updates for the following: FortiSandbox 4.4 – versions 4.4.0 to 4.4.8 FortiSandbox 5.0 – versions 5.0.0 to 5.0.5 FortiAnalyzer Cloud 7.6 – versions 7.6.2 to 7.6.4 FortiManager Cloud 7.6 – versions 7.6.2 to 7.6.4 FortiDDoS-F 7.2 – versions 7.2.1 to 7.2.2 Update 1 Open-source reporting indicates that CVE-2026-39813, CVE-2026-39808, and CVE-2026-25089 have been exploited. Update 2 On July 16, 2026, Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-39808 to their Known Exploited Vulnerabilities (KEV) Database. The Cyber Centre encourages users and administrators to review the provided web links and apply the necessary updates. OS Command Injection through API endpoint Unauthenticated Authentication bypass and Privilege escalation in FortiSandbox Heap-based buffer overflow in oftpd daemon SQL Injection via API Fortinet PSIRT Advisories CISA KEV : CVE-2026-39808
CSIRTS triage
- What
- There is an OS command injection vulnerability that allows unauthenticated attackers to execute unauthorized commands.
- Who is affected
- Users of FortiSandbox versions 4.4.0 to 4.4.8 and 5.0.0 to 5.0.5.
- Urgency
- Remediation is urgent due to confirmed exploitation of the vulnerability.
- Action
- Apply the necessary updates as recommended by Fortinet.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://cyber.gc.ca/en/alerts-advisories/fortinet-security-advisory-av26-351
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2026-39813Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 98% of all scored CVEs.
- Exploitation confirmedCVE-2026-39808Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all scored CVEs.
- Exploitation confirmedCVE-2026-25089Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 99% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-39813 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-39808 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-25089 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- criticalexploitedFortinet security advisory (AV26-568) – Update 1cccs
- highexploitedCISA Adds Three Known Exploited Vulnerabilities to Catalogcisa
- criticalexploitedCVE-2026-25089: Fortinet FortiSandbox OS Command Injection Vulnerabilitycisa-kev
- criticalexploitedCVE-2026-39808: Fortinet FortiSandbox OS Command Injection Vulnerabilitycisa-kev
- unknownSecond-Order OS Command Injection via JSON Input on start vnc featurefortinet
- unknownOS Command Injection through API endpointfortinet
- unknownUnauthenticated Authentication bypass and Privilege escalation in FortiSandboxfortinet
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