CVE-2021-29294
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 D-Link DSL-2740R UK_1.01, which could let a remove malicious user cause a denial of service via the send_hnap_unauthorized function. It could be triggered by sending crafted POST request to /HNAP1/. NOTE: The DSL-2740R and all hardware revisions are considered End of Life and as such this issue will not be patched
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 confidenceA Null Pointer Dereference vulnerability in the send_hpnap_unauthorized function of D-Link DSL-2740R UK_1.01 allows remote attackers to cause denial of service by sending a crafted POST request to the /HNAP1/ endpoint. The vulnerability stems from improper input validation when processing the HTTP request.
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= uk_1.01CVSS 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.
-
Identify device modelLog into the router web interface or check the device label to confirm the model is D-Link DSL-2740RAffected if Device is not a D-Link DSL-2740R, then not affected
-
Check firmware versionNavigate to the router admin panel, typically at 192.168.1.1, and locate the firmware version under Status or Device Info section. Compare against the affected version UK_1.01Affected if Firmware version is UK_1.01 - this is the exact affected version
-
Verify HNAP1 service is runningAttempt to access http://<device_ip>/HNAP1/ via HTTP GET request. A response (even an error) indicates the service is activeAffected if HNAP1 service responds - the vulnerable code path is present and accessible
-
Confirm network exposureCheck if the router admin interface (including /HNAP1/) is accessible from WAN/internet or untrusted networks. Test by attempting to reach the /HNAP1/ endpoint from an external IPAffected if HNAP1 endpoint is reachable from untrusted networks - remote exploitation is possible
Device is affected if it is a D-Link DSL-2740R running firmware UK_1.01 with the HNAP1 service exposed to network attackers.
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 · scopedSince D-Link has classified this device as End of Life with no patch forthcoming, the primary mitigation is to replace the affected device with a currently supported model. If immediate replacement is not feasible, network segmentation and firewall rules should be implemented to restrict unauthorized access to the /HNAP1/ endpoint.
- The D-Link DSL-2740R and all hardware revisions are End of Life (EOL) and will not receive a patch for this vulnerability.
- No vendor-provided fix is available for CVE-2021-29294.
- Consider replacing the affected device with a currently supported model from D-Link or another vendor.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29294 — 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-2021-29294 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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