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Internet GatekeeperApplication · F Secure

CVE-2021-33600

HIGH · 7.5 CVSS v3.1 Published 2021-09-28
Fix available
A fix is available. Upgrade to after 5.50.47 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 denial-of-service (DoS) vulnerability was discovered in the web user interface of F-Secure Internet Gatekeeper. The vulnerability occurs because of an attacker can trigger assertion via malformed HTTP packet to web interface. An unauthenticated attacker could exploit this vulnerability by sending a large username parameter. A successful exploitation could lead to a denial-of-service of the product.

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 denial-of-service vulnerability exists in the web user interface of F-Secure Internet Gatekeeper. The vulnerability is triggered when an unauthenticated attacker sends a malformed HTTP packet containing an excessively large username parameter to the web interface, causing an assertion failure. Successful exploitation results in the product becoming unavailable.

MitigationApply the vendor-supplied security update or patch for F-Secure Internet Gatekeeper when available. Consider restricting network access to the web interface via firewall or VPN to reduce exposure to unauthenticated attackers until the patch can be applied.

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
Internet GatekeeperApplication
Affected:>= 5.10, <= 5.50.47

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. Confirm F-Secure Internet Gatekeeper is installed
    Locate the installation directory or check system services for F-Secure Internet Gatekeeper process. Common locations include C:\Program Files\F-Secure or /opt/f-secure/ on Linux systems.
    Affected if The product is not present on the system, the vulnerability does not apply.
  2. Determine installed version
    Run the product's version check command, or inspect the version information in the product's about or status page within the web interface. Compare the installed version against the affected range: 5.10 through 5.50.47.
    Affected if The installed version falls within 5.10 <= version <= 5.50.47, indicating a potentially vulnerable version.
  3. Verify web interface is enabled
    Check if the web user interface service is running and accessible. This is typically accessible on port 8082 or 443. Attempt to reach the login page or check the service configuration.
    Affected if The web interface is disabled or not running, the denial-of-service trigger cannot be exploited.
  4. Assess network exposure of the web interface
    Review firewall rules, network configuration, or access control lists to determine if the web interface is reachable from untrusted networks. Check if it listens on external interfaces versus localhost only.
    Affected if The web interface is exposed to unauthenticated attackers on the network, enabling remote exploitation of this vulnerability.

A user is affected if F-Secure Internet Gatekeeper versions 5.10-5.50.47 is installed with the web interface enabled and accessible to unauthenticated network attackers.

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 5.50.47
Interim mitigation

Apply the vendor-supplied security update or patch for F-Secure Internet Gatekeeper when available. Consider restricting network access to the web interface via firewall or VPN to reduce exposure to unauthenticated attackers until the patch can be applied.

Recommended fix Moderate confidence

F-Secure Internet Gatekeeper 5.50.48 or later

  1. Identify the current installed version of F-Secure Internet Gatekeeper
  2. Confirm the version is within the affected range (5.10 through 5.50.47)
  3. Obtain F-Secure Internet Gatekeeper version 5.50.48 or later from F-Scure's official download portal
  4. Back up current configuration and policy settings
  5. Deploy the upgrade in a test environment to verify functionality
  6. Apply the upgrade to production environment
  7. Verify the service is running and the web interface is accessible
  8. Confirm the vulnerability is no longer reproducible
Caveat Review release notes for any deprecated features or configuration changes between current version and 5.50.48

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

Fix this in Internet Gatekeeper Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

Scan for this in your stack

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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-2021-33600 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