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FortiosOperating system · Fortinet

CVE-2017-14186

MEDIUM · 5.4 CVSS v3.0 Published 2017-11-29
Fix available
A fix is available. Upgrade to after 5.6.2 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 Cross-site Scripting (XSS) vulnerability in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.0 to 5.6.7, 5.4 and below versions under SSL VPN web portal allows a remote user to inject arbitrary web script or HTML in the context of the victim's browser via the login redir parameter. An URL Redirection attack may also be feasible by injecting an external URL via the affected parameter.

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

Cross-site scripting (XSS) vulnerability in Fortinet FortiOS SSL VPN web portal allows injection of arbitrary web script or HTML via the 'login_redir' parameter. The unsanitized parameter reflects user-supplied input back to the victim's browser, enabling session hijacking, credential theft, or phishing. An external URL redirection attack is also possible.

MitigationUpgrade FortiOS to version 5.6.8+, 6.0.5+, or 6.2+ to patch the vulnerability. As interim mitigation, disable the SSL VPN web portal or deploy WAF rules to validate and sanitize the login_redir parameter.

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:<= 5.0> 5.2.0, <= 5.2.12>= 5.4.0, <= 5.4.6>= 5.6.0, <= 5.6.2

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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 FortiOS version
    Access the FortiGate CLI and run the command 'get system status' or check the web UI dashboard to view the firmware version. Alternatively, check the FortiGuard download portal or device management console for the installed FortiOS version.
    Affected if The installed version falls within any of these ranges: 5.0 and below, 5.2.1 through 5.2.12, 5.4.0 through 5.4.6, or 5.6.0 through 5.6.2.
  2. Confirm SSL VPN web portal is enabled
    In the FortiGate web UI, navigate to VPN > SSL-VPN Settings, or run 'show vpn ssl settings' in the CLI. Check if 'Enable SSL-VPN' is toggled on and note the listening interface and port.
    Affected if SSL VPN web portal access is enabled and the FortiOS version is in an affected range.
  3. Test login_redir parameter for reflection
    Access the SSL VPN login page (typically at /ssl-vpn/login.esp) and modify the 'login_redir' parameter in the URL to include a test string such as 'login_redir=test<scr1pt>alert(1)</scr1pt>'. Submit the request and inspect the response to see if the payload reflects unchanged.
    Affected if The login_redir parameter reflects the unsanitized input in the HTTP response, indicating the XSS vulnerability is present.
  4. Test for external URL redirection
    Set the login_redir parameter to an external domain, for example 'login_redir=https://example.com', and observe if the application redirects to that external site after authentication or during the login process.
    Affected if The application redirects to the external URL specified in the login_redir parameter without validation.

You are affected if your FortiOS version is in the vulnerable ranges AND the SSL VPN web portal is enabled, since the login_redir parameter accepts and reflects unsanitized input leading to XSS or redirection.

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.

From vendor data
Upgrade available Upgrade to a release after 5.6.2
Interim mitigation

Upgrade FortiOS to version 5.6.8+, 6.0.5+, or 6.2+ to patch the vulnerability. As interim mitigation, disable the SSL VPN web portal or deploy WAF rules to validate and sanitize the login_redir parameter.

Fix this in Fortios 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-2017-14186 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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