CVE-2021-28845
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 · uneditedNull Pointer Dereference vulnerability exists in TRENDnet TEW-755AP 1.11B03, TEW-755AP2KAC 1.11B03, TEW-821DAP2KAC 1.11B03, and TEW-825DAP 1.11B03, which could let a remote malicious user cause a denial of service by sending the POST request to apply_cgi via the lang action without a language key.
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 null pointer dereference vulnerability exists in the web management interface of multiple TRENDnet wireless access point models (TEW-755AP, TEW-755AP2KAC, TEW-821DAP2KAC, TEW-825DAP) running firmware 1.11B03. The vulnerability is triggered by sending a specially crafted POST request to the apply_cgi endpoint with the lang action but omitting the language key parameter. This causes the device's web server to crash, resulting in denial of service.
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= 1.11b03= 1.11b03= 1.11b03= 1.11b03CVSS 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 device modelAccess the device's web management interface and navigate to the Status or System Information page to confirm the exact model number (TEW-755AP, TEW-755AP2KAC, TEW-821DAP2KAC, or TEW-825DAP). Alternatively, use network scanning tools to identify the device by its MAC vendor OUI (TRENDnet) or HTTP fingerprint.Affected if The device model matches one of: TEW-755AP, TEW-755AP2KAC, TEW-821DAP2KAC, or TEW-825DAP.
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Check firmware versionIn the device's web interface, go to the Status or System Information page and locate the Firmware Version field. Compare this version against 1.11B03.Affected if The firmware version is exactly 1.11B03.
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Verify web management interface is enabledAttempt to access the device's HTTP/HTTPS management interface via its IP address. Confirm the login page or apply_cgi endpoint responds to requests.Affected if The web management interface is accessible and responding.
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Confirm network exposureDetermine if the device's web interface is reachable from untrusted networks by checking routing tables, firewall rules, or VPN configurations that allow external access to the device's management IP.Affected if The web management interface is exposed to networks outside of trusted administrative segments.
You are affected if you have a TEW-755AP, TEW-755AP2KAC, TEW-821DAP2KAP, or TEW-825DAP device running firmware version 1.11B03 with the web management interface 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.
From vendor dataApply vendor-supplied firmware updates when available; in the interim, restrict access to the device's web management interface to trusted networks or disable remote administration.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-28845 — 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-2021-28845 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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