Critical

Unauthenticated RCE in Fortinet FortiSandbox Web UI

IdentifiersCVE-2026-26083CWE-862· Missing Authorization

CVE-2026-26083 is a critical missing authorization vulnerability in the Web UI/GUI of Fortinet FortiSandbox, FortiSandbox Cloud, and FortiSandbox PaaS. The flaw affects FortiSandbox 5.0.0 through 5.0.1, FortiSandbox 4.4.0 through 4.4.8, FortiSandbox Cloud 5.0.2 through 5.0.5, FortiSandbox PaaS 5.0.0 through 5.0.1, FortiSandbox PaaS 4.4.5 through 4.4.8, and all versions of legacy FortiSandbox PaaS 23.4, 23.3, 23.1, 22.2, 22.1, 21.4, and 21.3. Due to missing authorization checks in the Web UI, a remote attacker can send crafted HTTP requests to invoke restricted functionality and execute unauthorized code or commands. Public reporting describes the issue as reachable without authentication and without user interaction, resulting in remote code execution on vulnerable systems.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can lead to remote arbitrary code or command execution on the affected FortiSandbox system. Because exploitation is unauthenticated and network-reachable over the Web UI, compromise can affect confidentiality, integrity, and availability of the appliance or service. Reporting also notes potential access to restricted functionality and sensitive sandbox analysis data, which could undermine malware-analysis workflows and broader security monitoring dependent on FortiSandbox.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, prioritize restricting exposure of the FortiSandbox Web UI, especially for internet-facing deployments. Limit access to trusted administrative networks, place the interface behind VPN or equivalent access controls, and monitor HTTP/Web UI logs for crafted or anomalous requests targeting administrative functionality. Because the flaw is unauthenticated, reducing network reachability to the GUI is the primary interim mitigation until patched or migrated.

Remediation

Patch, then assume compromise.

Apply Fortinet’s fixed releases referenced in PSIRT advisory FG-IR-26-136. Reported fixed versions include: FortiSandbox 5.0.2 or later for 5.0.0-5.0.1; FortiSandbox 4.4.9 or later for 4.4.0-4.4.8; FortiSandbox Cloud 5.0.6 or later for 5.0.2-5.0.5; FortiSandbox PaaS 5.0.2 or later for 5.0.0-5.0.1; and FortiSandbox PaaS 4.4.9 or later for 4.4.5-4.4.8. For legacy affected FortiSandbox Cloud 23/24 and FortiSandbox PaaS 23.4, 23.3, 23.1, 22.2, 22.1, 21.4, and 21.3, migrate immediately to a supported fixed release as advised by Fortinet.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Fortinet Fortisandbox Paasapplication

FortinetFortisandboxapplication

FortinetFortisandbox Cloudapplication

FortinetFortisandboxcloudapplication

FortinetFortisandboxpaasapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

18 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

18 SOURCESView more in app

bleeping computerNews

Jun 16, 2026

Critical Fortinet FortiSandbox flaws now exploited in attacks

A critical Fortinet FortiSandbox vulnerability that could allow remote code execution on unpatched systems.

cyberthroneNews

May 16, 2026

Fortinet Patch Tuesday - May 2026 - TheCyberThrone

A critical missing authorization vulnerability in FortiSandbox products that could allow remote unauthenticated code or command execution through crafted HTTP requests to the web UI.

scworldNews

May 13, 2026

Fortinet addresses critical vulnerabilities in FortiSandbox and FortiAuthenticator | brief | SC Media

A critical unauthenticated remote code execution vulnerability in FortiSandbox that allows attackers to execute unauthorized code or commands via HTTP requests.

security affairsNews

May 13, 2026

Critical fortinet vulnerabilities fixed in FortiSandbox and FortiAuthenticator

A critical missing authorization vulnerability in FortiSandbox that may allow an unauthenticated attacker to execute unauthorized code or commands via HTTP requests, resulting in remote code execution.

+3 more in the timeline

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity10

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-26083

NVD

nvd.nist.gov/vuln/detail/CVE-2026-26083

MITRE CWE · CWE-862

Missing Authorization

Vendor Advisory

fortiguard.fortinet.com/psirt/FG-IR-26-136