CVE-2021-21730
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 ZTE product is impacted by improper access control vulnerability. The attacker could exploit this vulnerability to access CLI by brute force attacks.This affects: ZXHN H168N V3.5.0_TY.T6
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 confidenceThe ZTE ZXHN H168N router version V3.5.0_TY.T6 contains an improper access control vulnerability that allows attackers to bypass authentication mechanisms through brute force attacks, gaining unauthorized access to the device's CLI (Command Line Interface). This is a critical authentication failure that enables complete administrative control over the affected device.
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= 3.5.0_ty.t6CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 router modelCheck the device label or web management interface for the exact model number (ZXHN H168N)Affected if The device is not a ZTE ZXHN H168N router, then this CVE does not apply
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Verify the firmware versionAccess the router's web UI or CLI and check the firmware version string; look for '3.5.0_ty.t6' specificallyAffected if The installed firmware is NOT version 3.5.0_ty.t6, the device is not affected by this specific CVE
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Determine CLI accessibilityCheck if the router's command line interface is accessible over the network (LAN or WAN) or only from a directly connected console portAffected if The CLI is network-accessible from untrusted segments, the device is vulnerable to the brute force attack described in this CVE
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Review authentication logsExamine router logs or system logs for failed authentication attempts, repeated login failures, or unexpected administrative sessionsAffected if There are signs of brute force attempts or unauthorized CLI access, the vulnerability may have been exploited
You are affected if you have a ZTE ZXHN H168N router running firmware version exactly 3.5.0_ty.t6 with its CLI management interface exposed to a network where attackers could attempt brute force authentication.
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 the vendor-supplied firmware patch/update for the ZXHN H168N V3.5.0_TY.T6. Until patched, restrict network access to the device's management interface and monitor for brute force attempts.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-21730 — 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-2021-21730 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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