CVE-2020-11503
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 · uneditedA heap-based buffer overflow in the awarrensmtp component of Sophos XG Firewall v17.5 MR11 and older potentially allows an attacker to run arbitrary code remotely.
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 confidenceA heap-based buffer overflow vulnerability exists in the awarrensmtp component of Sophos XG Firewall v17.5 MR11 and older. The flaw allows remote attackers to potentially execute arbitrary code by overflowing a heap-allocated buffer in the SMTP processing module.
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< 17.5= 17.5CVSS 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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Identify Sophos XG Firewall versionAccess the firewall admin console and navigate to System > Backup and Firmware, or run 'sfos --version' via CLI if available. Record the exact firmware version number and MR patch level.Affected if The installed version is 17.5 MR11 or any version lower than 17.5 (e.g., 17.0, 16.x)
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Confirm awarrensmtp component statusAccess the firewall via CLI or admin interface and check the status of the awarrensmtp service. Look for SMTP-related services or the awarrensmtp daemon in the running processes or services list.Affected if The awarrensmtp component is running or enabled on the firewall.
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Verify SMTP service configurationNavigate to the SMTP proxy or mail settings in the Sophos XG admin console. Check if the SMTP service is enabled and which interfaces it is bound to (LAN, WAN, or both).Affected if The SMTP service is enabled and accessible, particularly if exposed on external/WAN interfaces.
A user is affected if their Sophos XG Firewall runs version 17.5 or older and has the awarrensmtp/SMTP service enabled and accessible.
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 · scoped17.5
Upgrade Sophos XG Firewall to a version newer than v17.5 MR11 that contains the security patch. If immediate patching is not possible, restrict network access to the SMTP service and implement additional firewall filtering.
Sophos XG Firewall v17.5 MR12 or later
- 1. Access Sophos XG Firewall admin console
- 2. Navigate to System > Firmware or check for updates
- 3. Ensure firmware version is updated to v17.5 MR12 or later which contains the security fix for the awarrensmtp heap-based buffer overflow (CVE-2020-11503)
- 4. After upgrade, verify the awarrensmtp service is running correctly
- 5. Test mail relay functionality to ensure the SMTP service operates normally
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
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-11503 — 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-2020-11503 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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