CVE-2021-20993
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 · uneditedIn multiple managed switches by WAGO in different versions the activated directory listing provides an attacker with the index of the resources located inside the directory.
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 confidenceThis vulnerability allows directory listing on WAGO managed switches, exposing the index of files and resources within directories. An attacker can enumerate files, potentially revealing sensitive configuration files, backups, or other system resources that should not be publicly accessible.
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<= 1.2.3.s0<= 1.1.7.s0<= 1.1.6.s0<= 1.0.4.s0<= 1.0.4.s0CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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 WAGO switch modelCheck the device label or access the web interface to confirm the model number matches the 0852 series (0852 0303, 0852 1305, 0852 1505, or their /000 001 variants)Affected if Device is NOT a WAGO 0852 series switch - not affected
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Check firmware versionAccess the device web interface or use SNMP/CLI to retrieve the firmware version. For 0852 0303: compare to 1.2.3.s0. For 0852 1305: compare to 1.1.7.s0. For 0852 1505: compare to 1.1.6.s0. For /000 001 variants: compare to 1.0.4.s0Affected if Firmware version is equal to or lower than the specified version for your model
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Verify web interface is accessibleAttempt to access the device web interface via HTTP/HTTPS on the management IP addressAffected if Web interface is not accessible - cannot confirm the vulnerability
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Test for directory listing exposureNavigate to common directories on the web interface such as /, /cgi-bin/, /backup/, /config/, or any directory path and observe if a directory listing is returned showing file indexes instead of a 403 Forbidden or default pageAffected if Directory listing is displayed showing file indexes - vulnerability is present
If the device is a WAGO 0852 series switch with firmware at or below the affected version AND directory listing is exposed via the web interface, the environment is affected by CVE-2021-20993
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 dataDisable directory listing in the web server configuration on affected WAGO switches, or apply vendor-supplied firmware updates that disable this feature by default.
- Consultation4.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20993 — 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-2021-20993 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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