CVE-2021-20996
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 special crafted requests can lead to cookies being transferred to third parties.
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 confidenceThis vulnerability in WAGO managed switches allows specially crafted requests to cause cookies (likely session cookies) to be transmitted to third-party domains. The issue stems from improper handling of cookie attributes or cross-domain request policies, potentially exposing session credentials to unauthorized parties.
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 the WAGO switch modelAccess the device web interface or use SNMP/CLI to retrieve the exact model number. Look for model identifiers 0852 0303, 0852 1305, 0852 1505, or their /000 001 variants.Affected if The device model matches any of the affected WAGO 0852 series switches.
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Determine the installed firmware versionVia web interface: Navigate to System > Information or similar firmware status page. Via CLI: Use 'show version' or 'system info' command. Record the exact firmware version string.Affected if The firmware version is at or below 1.2.3.s0 for model 0852 0303, 1.1.7.s0 for 0852 1305, 1.1.6.s0 for 0852 1505, or 1.0.4.s0 for /000 001 variants.
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Verify web management interface is enabledCheck if the HTTP/HTTPS web interface is accessible by attempting to reach the device IP on ports 80 or 443. Confirm the WAGO login page loads.Affected if The web interface is exposed and accessible, as this is required for the specially crafted requests to reach the vulnerability.
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Inspect cookie attributes on authenticated sessionsLog into the device web interface, open browser developer tools (F12), go to Application/Storage tab, and examine cookies for the session. Check for SameSite, Secure, and HttpOnly attributes.Affected if Cookies lack SameSite attribute (or have SameSite=None without Secure) and are being set, indicating potential exposure to third-party domains.
You are affected if you have a WAGO 0852 series switch running firmware at or below the version thresholds AND the web management interface is enabled, allowing crafted requests to transmit cookies to third-party domains.
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 dataImplement SameSite=Strict or SameSite=Lax attributes on all cookies, enable Secure and HttpOnly flags, and restrict cross-domain cookie sharing. If available, apply vendor firmware patches and isolate affected devices in a secured network segment.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20996 — 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-2021-20996 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
- No spam, self-promotion, credentials, or personal data