CVE-2026-39808
Actively exploited. CVE-2026-39808 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-07-16) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2026-39808 is indexed in GitHub PoC and Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
CISA has added three new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog , based on evidence of active exploitation. CVE-2026-25089 Fortinet FortiSandbox OS Command Injection Vulnerability CVE-2026-39808 Fortinet FortiSandbox OS Command Injection Vulnerability CVE-2026-58644 Microsoft SharePoint Deserialization of Untrusted Data Vulnerability These types of vulnerabilities are frequent attack vectors for malicious cyber actors and pose significant risks to the federal enterprise. Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied. While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities . CISA will continue to add vulnerabilities to the catalog that meet the specified criteria . Aware of an exploited vulnerability not currently listed in the KEV Catalog? Submit it for potential addition through CISA’s KEV Nomination Form . Potential KEV additions must have a CVE ID, evidence of exploitation, and clear mitigation guidance.
CSIRTS triage
- What
- CISA has added multiple vulnerabilities to its KEV Catalog, indicating active exploitation.
- Who is affected
- Federal agencies and users of Fortinet products.
- Urgency
- High urgency for remediation due to the risk posed by these vulnerabilities.
- Action
- Prioritize updates as per the KEV Catalog recommendations.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 99.8% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2026-39808 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
- NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗
Advisory coverage (4)
- criticalexploitedFortinet security advisory (AV26-351) – Update 2cccs · 2026-07-16
- highexploitedCISA Adds Three Known Exploited Vulnerabilities to Catalogcisa · 2026-07-16
- criticalexploitedCVE-2026-39808: Fortinet FortiSandbox OS Command Injection Vulnerabilitycisa-kev · 2026-07-16
- unknownexploitedOS Command Injection through API endpointfortinet · 2026-04-14
External references
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[](https://www.csirts.com/cve/CVE-2026-39808)