CVE-2025-6704
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 · uneditedAn arbitrary file writing vulnerability in the Secure PDF eXchange (SPX) feature of Sophos Firewall versions older than 21.0 MR2 (21.0.2) can lead to pre-auth remote code execution, if a specific configuration of SPX is enabled in combination with the firewall running in High Availability (HA) mode.
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 confidenceArbitrary file write vulnerability in the Secure PDF eXchange (SPX) feature of Sophos Firewall allows pre-auth remote code execution when SPX is configured specifically and the firewall runs in High Availability mode. Versions prior to 21.0.2 are affected.
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< 21.0.2CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/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 checksWork through these to decide whether this CVE applies to you.
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Check Sophos Firewall firmware versionLog into the firewall admin console and navigate to System > Administration > System Info, or run 'version' command via CLI to retrieve the installed firmware version.Affected if Firmware version is below 21.0.2 (prior to 21.0 MR2)
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Verify SPX feature configurationNavigate to the Secure PDF eXchange (SPX) settings in the admin console under Mail > SPX, or check via CLI command 'spx config show' if available, to determine if SPX is configured or enabled.Affected if SPX is configured or enabled on the firewall
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Check High Availability mode statusNavigate to High Availability settings in the admin console under System > High Availability, or use CLI command 'ha status' to determine if HA mode is active.Affected if High Availability mode is enabled or active
All three conditions must be true for exploitation: firmware version below 21.0.2 AND SPX configured AND High Availability mode enabled.
Generated from the published advisory. Verify against your own configuration.
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 · scoped21.0.2
Upgrade to Sophos Firewall 21.0 MR2 (21.0.2) or later. As an interim measure, disable SPX if not required and/or avoid HA mode until the upgrade can be performed.
21.0.2 (21.0 MR2)
- Verify current Sophos Firewall firmware version via the web admin console or CLI
- Download Sophos Firewall firmware version 21.0.2 (or 21.0 MR2) from the official Sophos download portal
- Upload the firmware upgrade file through the Sophos Firewall admin interface (System > Firmware > Upload) or via SCP/CLI
- Schedule the upgrade during a maintenance window as the firewall will reboot
- After reboot, verify the new firmware version is 21.0.2 or later
- Confirm the SPX feature configuration and HA mode are working as expected post-upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation6.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-6704 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-6704 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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