CVE-2020-5137
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 buffer overflow vulnerability in SonicOS allows a remote unauthenticated attacker to cause Denial of Service (DoS) on the firewall SSLVPN service and leads to firewall crash. This vulnerability affected SonicOS Gen 5 version 5.9.1.7, 5.9.1.13, Gen 6 version 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv 6.5.4.v and Gen 7 version 7.0.0.0.
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 buffer overflow vulnerability in SonicOS SSLVPN service allows remote unauthenticated attackers to send specially crafted requests that overflow a buffer, causing denial of service and complete firewall crash. This affects multiple generations of SonicWall firewall firmware including Gen 5 (5.9.1.7, 5.9.1.13), Gen 6 (6.5.4.7, 6.5.1.12, 6.0.5.3), SonicOSv (6.5.4.v), and Gen 7 (7.0.0.0).
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<= 5.9.1.13>= 6.0.0.0, <= 6.0.5.3>= 6.5.0.0, <= 6.5.1.11>= 6.5.4.0, <= 6.5.4.7= 7.0.0.0<= 6.5.4.4CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the SonicOS firmware versionAccess the SonicWall management interface (web UI or CLI) and navigate to System > Status or use the 'show version' command in CLI to retrieve the installed firmware versionAffected if The installed version falls within any of these ranges: SonicOS <= 5.9.1.13, 6.0.0.0 to 6.0.5.3, 6.5.0.0 to 6.5.1.11, 6.5.4.0 to 6.5.4.7, or exactly 7.0.0.0; SonicOSv <= 6.5.4.4
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Confirm the SSLVPN service is enabledIn the SonicWall web UI, navigate to VPN > SSL VPN Settings or check the service status via CLI using 'show sslvpn status' to determine if the SSLVPN feature is activeAffected if The SSLVPN service is enabled and accessible from network interfaces
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Verify SSLVPN is accessible from untrusted networksReview the SSLVPN listen interface configuration in VPN > SSL VPN Settings to identify which IP addresses or interfaces the service binds to (such as WAN or all interfaces)Affected if SSLVPN is bound to WAN-facing interfaces or accessible from untrusted networks without proper network-level filtering
You are affected if your SonicWall device runs a vulnerable SonicOS or SonicOSv version AND has SSLVPN enabled and exposed to potentially untrusted networks.
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.
From vendor dataApply vendor-supplied patches for affected SonicOS versions. If patches are unavailable, restrict or disable SSLVPN access and implement network-level filtering to limit exposure to untrusted networks.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-5137 — 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-2020-5137 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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