dbcve.org
Firewall FirmwareOperating system · Sophos

CVE-2024-13974

HIGH · 8.1 CVSS v3.1 Published 2025-07-21
Fix available
A fix is available. Upgrade to 21.0.1 or later.
See remediation →
90/100
Remediation priority · Urgent
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 business logic vulnerability in the Up2Date component of Sophos Firewall older than version 21.0 MR1 (20.0.1) can lead to attackers controlling the firewall’s DNS environment to achieve remote code 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 business logic vulnerability in the Up2Date component of Sophos Firewall versions older than 21.0 MR1 (20.0.1) allows attackers to manipulate the firewall's DNS environment, which can be leveraged to achieve remote code execution on the affected device.

MitigationUpgrade Sophos Firewall to version 21.0 MR1 or later to remediate this vulnerability. If immediate upgrade is not feasible, restrict management interface access to trusted networks and monitor DNS configuration changes.

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
Firewall FirmwareOperating system
Affected:< 21.0.1

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

CVSS:3.1/AV:N/AC:H/PR:N/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. Check Sophos Firewall firmware version
    Log into the firewall management interface and navigate to System Services > About, or run 'version' command in the console to display the firmware version
    Affected if The firmware version is older than 21.0.1 (such as 20.0.0, 19.5, 18.x, etc.)
  2. Verify Up2Date component status
    In the web admin interface, go to System Services > Up2Date to view the Up2Date configuration and connection status
    Affected if Up2Date service is enabled and configured on the firewall
  3. Review DNS server configuration
    Navigate to Network > DNS in the firewall admin interface and inspect the configured primary and secondary DNS servers
    Affected if DNS servers are set to external or untrusted sources that could be manipulated
  4. Check management interface exposure
    In the firewall interface, go to Administration > Admin User and verify which IP addresses have management access, or check firewall rules allowing management access
    Affected if Management interface is accessible from untrusted networks (0.0.0.0/0 or internet-facing IPs)

The environment is affected if Sophos Firewall firmware is below version 21.0.1 and the Up2Date component is enabled, as this combination allows the DNS manipulation attack vector.

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 21.0.1 or later
Fixed in 21.0.1
Interim mitigation

Upgrade Sophos Firewall to version 21.0 MR1 or later to remediate this vulnerability. If immediate upgrade is not feasible, restrict management interface access to trusted networks and monitor DNS configuration changes.

Recommended fix High confidence

Sophos Firewall Firmware 21.0.1 or later (21.0 MR1)

  1. 1. Access the Sophos Firewall management interface
  2. 2. Navigate to System Settings > Firmware or Updates section
  3. 3. Check the current firmware version to confirm it is below 21.0.1
  4. 4. Download the latest firmware version 21.0.1 or later from the Sophos download portal
  5. 5. Upload the firmware file to the firewall
  6. 6. Initiate the firmware upgrade process
  7. 7. After upgrade completes, verify the version shows 21.0.1 or higher
  8. 8. Confirm the Up2Date service is functioning correctly and receiving updates
Caveat Review Sophos release notes for 21.0.1 for any configuration or feature changes before upgrading

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

Fix this in Firewall Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2024-13974 in production — separate from our analysis above.

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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