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FortiwebApplication · Fortinet

CVE-2021-36179

HIGH · 8.8 CVSS v3.1 Published 2021-09-08
Fix available
A fix is available. Upgrade to after 6.3.14 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 stack-based buffer overflow in Fortinet FortiWeb version 6.3.14 and below, 6.2.4 and below allows attacker to execute unauthorized code or commands via crafted parameters in CLI command execution

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 · moderate confidence

A stack-based buffer overflow vulnerability in Fortinet FortiWeb's CLI command execution allows attackers to execute arbitrary code or commands via crafted parameters. The vulnerability stems from insufficient bounds checking when processing input in CLI commands, enabling malicious payload injection onto the stack.

MitigationUpgrade FortiWeb to version 6.3.15 or later (for the 6.3 branch) or 6.2.5 or later (for the 6.2 branch) to receive the vendor patch. If immediate patching is not feasible, restrict CLI access to trusted management networks only.

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:<= 6.2.4>= 6.3.0, <= 6.3.14

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. Determine FortiWeb version
    Log into the FortiWeb CLI and run the command to display system information, such as 'get system status' or 'diagnose system version'. This displays the installed FortiWeb firmware version.
    Affected if The version displayed is 6.2.4 or lower, OR is 6.3.0 through 6.3.14.
  2. Verify CLI access is enabled
    Check if the FortiWeb CLI is accessible via SSH or console connection. Confirm that administrative access is permitted on the interface(s) used for management.
    Affected if CLI access is enabled and reachable from your management network.
  3. Assess CLI exposure to untrusted networks
    Review network configurations to determine if port 22 (SSH) or console access for FortiWeb CLI is exposed to untrusted or public networks rather than being restricted to a trusted management subnet.
    Affected if The CLI interface is reachable from networks that are not explicitly trusted.
  4. Confirm affected version range
    Compare your identified FortiWeb version against the vulnerable ranges: any version <= 6.2.4 or between 6.3.0 and 6.3.14 inclusive is affected by this vulnerability.
    Affected if The installed version falls within the affected ranges specified in the CVE.

You are affected if your FortiWeb version is 6.2.4 or lower, or between 6.3.0 and 6.3.14, and the CLI 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 a release after 6.3.14
Interim mitigation

Upgrade FortiWeb to version 6.3.15 or later (for the 6.3 branch) or 6.2.5 or later (for the 6.2 branch) to receive the vendor patch. If immediate patching is not feasible, restrict CLI access to trusted management networks only.

Recommended fix Moderate confidence

FortiWeb 6.2.5 or later, or FortiWeb 6.3.15 or later (or latest stable 6.4.x/7.x if compatible)

  1. Identify the current FortiWeb version by running: get system status or checking the web UI dashboard
  2. Determine if the current version falls within affected ranges: <= 6.2.4 or >= 6.3.0 and <= 6.3.14
  3. If affected, plan for upgrade to a fixed release above 6.2.4 and 6.3.14
  4. Backup current FortiWeb configuration before upgrading
  5. Schedule maintenance window as upgrades may require downtime
  6. Download the fixed FortiWeb firmware from Fortinet Customer Support portal (https://support.fortinet.com)
  7. Upload and install the new firmware via web UI (System > Firmware) or CLI
  8. Verify the upgrade was successful and test normal operations
Caveat Review Fortinet release notes for the target version for compatibility notes and potential configuration changes; some upgrades may require specific upgrade paths

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

Fix this in Fortiweb Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2021-36179 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