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FortiosOperating system · Fortinet

CVE-2022-27491

HIGH · 7.5 CVSS v3.1 Published 2022-09-06
Fix available
A fix is available. Upgrade to 6.2.11 / 6.4.9 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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 verification of source of a communication channel in Fortinet FortiOS with IPS engine version 7.201 through 7.214, 7.001 through 7.113, 6.001 through 6.121, 5.001 through 5.258 and before 4.086 allows a remote and unauthenticated attacker to trigger the sending of "blocked page" HTML data to an arbitrary victim via crafted TCP requests, potentially flooding the victim.

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

This vulnerability in FortiOS IPS engine allows an unauthenticated remote attacker to send crafted TCP requests that trigger the firewall to send 'blocked page' HTML responses to an arbitrary victim. The lack of proper source verification enables the FortiOS device to be abused as a reflector/amplifier for flooding attacks against third parties.

MitigationApply the Fortinet patches for the specific FortiOS versions (upgrade to fixed versions: 7.215 or later, 7.114 or later, 6.122 or later, 5.259 or later, 4.086 or later) or enable IPS signatures if available as a compensating control.

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
FortiosOperating system
Affected:>= 6.0.0, <= 6.0.14>= 6.2.0, < 6.2.11>= 6.4.0, < 6.4.9>= 7.0.0, < 7.0.6= 7.2.0

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 FortiOS version
    Run 'get system status' or 'fortios -v' via CLI or check in web UI under Dashboard > Status
    Affected if Version falls within >= 6.0.0 <= 6.0.14, >= 6.2.0 < 6.2.11, >= 6.4.0 < 6.4.9, >= 7.0.0 < 7.0.6, or equals 7.2.0
  2. Verify IPS engine is enabled
    Run 'get ips status' or check in web UI under Security Fabric > Intrusion Prevention
    Affected if IPS sensor is actively inspecting traffic and the FortiOS version is in the affected range
  3. Check management interface exposure
    Run 'get system interface' to list interfaces with management access, or review 'config system interface' settings for 'set allowaccess' containing HTTPS or HTTP
    Affected if Management or IPS-facing interface is accessible from untrusted networks (0.0.0.0/0 or external interfaces)
  4. Confirm IPS signature database is current
    Run 'ips manual' or check 'get ips signatures' to see last update timestamp and signature version
    Affected if Running an affected FortiOS version with outdated IPS signatures (legacy compensating control not applied)

The environment is affected if the FortiOS version matches any of the listed vulnerable ranges and the IPS engine processes traffic from unauthenticated sources.

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 6.2.11 / 6.4.9 / 7.0.6 or later
Fixed in 6.2.116.4.97.0.6
Interim mitigation

Apply the Fortinet patches for the specific FortiOS versions (upgrade to fixed versions: 7.215 or later, 7.114 or later, 6.122 or later, 5.259 or later, 4.086 or later) or enable IPS signatures if available as a compensating control.

Recommended fix High confidence

Upgrade to FortiOS 6.0.15, 6.2.11, 6.4.9, or 7.0.6 (depending on current branch)

  1. 1. Identify the currently installed FortiOS version using 'get system status' command
  2. 2. Based on the current version, plan upgrade to the fixed release: 6.0.15+ for 6.0.x branch, 6.2.11 for 6.2.x branch, 6.4.9 for 6.4.x branch, or 7.0.6 for 7.0.x branch
  3. 3. Backup current FortiOS configuration using 'execute backup config' command
  4. 4. Download the appropriate firmware image from Fortinet customer support portal (fortinet.com/support)
  5. 5. Upload firmware via FortiOS web UI (System > Firmware) or CLI: 'execute firmware upgrade'
  6. 6. Verify the upgrade was successful and system is operational
  7. 7. Confirm the new version is running using 'get system status'
Caveat Review FortiOS release notes for the target 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 Fortios Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2022-27491 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