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FortiwebApplication · Fortinet

CVE-2021-41026

MEDIUM · 6.5 CVSS v3.1 Published 2022-04-06
Fix available
A fix is available. Upgrade to 6.3.16 / 6.4.2 or later.
See remediation →
71/100
Remediation priority · Elevated
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 relative path traversal in FortiWeb versions 6.4.1, 6.4.0, and 6.3.0 through 6.3.15 may allow an authenticated attacker to retrieve arbitrary files from the underlying filesystem via specially crafted web 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

A relative path traversal vulnerability in FortiWeb allows authenticated attackers to use directory traversal sequences (e.g., ../) in web requests to access files outside the intended web root, potentially exposing sensitive system files.

MitigationApply the vendor-supplied patch or upgrade to a fixed FortiWeb version. If patching is not immediately possible, restrict administrative access to trusted IP addresses and implement additional input validation at upstream layers.

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:>= 6.3.0, < 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
None
Availability
None

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

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. Identify FortiWeb installed version
    Access the FortiWeb CLI and run: get system status or via web UI go to System > Status to view the firmware version
    Affected if The displayed version falls within >= 6.3.0 and < 6.3.16, or >= 6.4.0 and < 6.4.2
  2. Verify web UI or API is accessible
    Confirm that the FortiWeb web management interface or REST API is enabled and reachable on the configured port (typically 443 or 8080)
    Affected if The web interface is exposed and the FortiWeb version is in the affected range
  3. Check for existing exploitation signs
    Review FortiWeb logs under Log & Report > Traffic Log or System Event Log for entries containing ../ sequences or unusual file access patterns in the URL parameters
    Affected if Log entries show directory traversal attempts or unauthorized file access to paths outside the web root

Your FortiWeb is affected if the installed firmware version is 6.3.0 through 6.3.15 or 6.4.0 through 6.4.1 and the web management interface is accessible to an authenticated attacker.

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 6.3.16 / 6.4.2 or later
Fixed in 6.3.166.4.2
Interim mitigation

Apply the vendor-supplied patch or upgrade to a fixed FortiWeb version. If patching is not immediately possible, restrict administrative access to trusted IP addresses and implement additional input validation at upstream layers.

Recommended fix High confidence

FortiWeb 6.3.16 or 6.4.2 (or later stable releases)

  1. 1. Backup the current FortiWeb configuration using the web UI or CLI (execute 'execute backup config' or use System > Maintenance > Backup & Restore)
  2. 2. Download FortiWeb firmware version 6.3.16 or 6.4.2 (or later) from the Fortinet Support Portal (support.fortinet.com)
  3. 3. Upload the firmware file via FortiWeb web UI (System > Maintenance > Firmware) or CLI (execute upgrade system <image-file>)
  4. 4. Follow Fortinet's documented upgrade procedure, ensuring stable power and network connectivity during the process
  5. 5. After reboot, verify the new version is running (get system status) and confirm the configuration was preserved
  6. 6. Validate that the path traversal vulnerability is fixed by ensuring authenticated users cannot access files outside the intended web root
Caveat Review Fortinet release notes for each intermediate version between your current version and the target fixed version for any configuration or feature changes that may require adjustment

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

Fix this in Fortiweb Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.

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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-2021-41026 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