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FortiwebApplication · Fortinet

CVE-2021-41018

HIGH · 8.8 CVSS v3.1 Published 2022-02-02
Fix available
A fix is available. Upgrade to 6.2.7 / 6.3.16 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A improper neutralization of special elements used in an os command ('os command injection') in Fortinet FortiWeb version 6.4.1 and below, 6.3.15 and below allows attacker to execute unauthorized code or commands via crafted HTTP requests.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

FortiWeb versions 6.4.1 and below and 6.3.15 and below contain an OS command injection vulnerability in the web interface. Attackers can craft malicious HTTP requests containing shell metacharacters that get executed on the underlying operating system due to insufficient input sanitization, allowing arbitrary code execution with the privileges of the affected service.

MitigationUpgrade FortiWeb to version 6.4.2, 6.3.16, or later per Fortinet's release notes. If immediate patching is not feasible, restrict network access to the FortiWeb management interface to trusted IP addresses or VPN-only access.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FortiwebApplication
Affected:>= 6.2.0, < 6.2.7>= 6.3.0, < 6.3.16>= 6.4.0, < 6.4.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check FortiWeb version via CLI
    Run the command: get system status or exec system version from the FortiWeb CLI console
    Affected if The displayed version falls within these ranges: 6.2.0 to 6.2.6, 6.3.0 to 6.3.15, or 6.4.0 to 6.4.1
  2. Confirm web interface is enabled
    Run: get system interface in CLI to list management interfaces, then check if the web UI (HTTP/HTTPS) is listed as enabled on any interface
    Affected if The web interface (port 80/443 or HTTP/HTTPS) is accessible on a management or external interface
  3. Verify web UI access is not restricted
    Check firewall policies or IP restrictions: run get firewall address and get firewall policy to see if source IPs are restricted to trusted networks only
    Affected if The management web interface is open to untrusted networks or has no IP whitelist applied
  4. Identify exposed management interfaces
    Run: diagnose network interface list and review which interfaces have HTTP/HTTPS services bound, particularly those with 'wan' or public-facing designations
    Affected if The web interface is bound to an interface reachable from untrusted networks

You are affected if FortiWeb is running version 6.2.0-6.2.6, 6.3.0-6.3.15, or 6.4.0-6.4.1 AND the web management interface is accessible from your network.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.2.7 / 6.3.16 / 6.4.2 or later
Fixed in 6.2.76.3.166.4.2
Interim mitigation

Upgrade FortiWeb to version 6.4.2, 6.3.16, or later per Fortinet's release notes. If immediate patching is not feasible, restrict network access to the FortiWeb management interface to trusted IP addresses or VPN-only access.

Recommended fix High confidence

FortiWeb 6.2.7, 6.3.16, or 6.4.2 (or latest stable release in respective branch)

  1. 1. Identify the currently installed FortiWeb version via the Web UI (System > Status) or CLI: 'get system status'
  2. 2. Determine which version branch you are running (6.2.x, 6.3.x, or 6.4.x)
  3. 3. For FortiWeb 6.2.x: upgrade to version 6.2.7 or later
  4. 4. For FortiWeb 6.3.x: upgrade to version 6.3.16 or later
  5. 5. For FortiWeb 6.4.x: upgrade to version 6.4.2 or later
  6. 6. Download the appropriate firmware from Fortinet's support portal (support.fortinet.com)
  7. 7. Back up the FortiWeb configuration before upgrading
  8. 8. Upload and install the firmware via Web UI (System > Maintenance > Firmware) or CLI: 'execute firmware upgrade'
Caveat Standard FortiWeb firmware upgrade risks apply - review release notes for migration considerations and ensure compatibility with connected infrastructure

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fortiweb Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,300
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-41018 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data