CVE-2021-21729
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 · uneditedSome ZTE products have CSRF vulnerability. Because some pages lack CSRF random value verification, attackers could perform illegal authorization operations by constructing messages.This affects: ZXHN H168N V3.5.0_EG1T5_TE, V2.5.5, ZXHN H108N V2.5.5_BTMT1
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 confidenceCSRF vulnerability in ZTE router firmware (ZXHN H168N and H108N models) where certain web management pages lack anti-CSRF token validation. Attackers can trick authenticated users into submitting unintended configuration changes or administrative actions by embedding malicious requests.
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_eg1t5_te= 2.5.5_btmt1CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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 router modelLocate the model label on the router physical device or log into the web admin panel and check the status or system information page for the exact model designation (ZXHN H168N or H108N)Affected if Router is not an ZXHN H168N or H108N model
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Check installed firmware versionLog into the router web management interface (typically at 192.168.1.1 or 192.168.0.1), navigate to Administration, Status, or System Info section, and record the firmware version stringAffected if Firmware version is 3.5.0_eg1t5_te (for H168N) or 2.5.5_btmt1 (for H108N)
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Verify web management interface accessibilityAttempt to access the router web interface from the local LAN (default) and if applicable, from WAN by entering the router's public IP in a browser. Confirm the login page loads.Affected if Web management interface is accessible from WAN (internet-facing)
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Check WAN remote management settingLog into the router admin panel, navigate to Network Settings, WAN Management, or Remote Access configuration, and determine if remote WAN management/HTTP access from WAN is enabledAffected if Remote WAN management is enabled and the web interface is internet-accessible
You are affected if your router is an ZXHN H168N running firmware 3.5.0_eg1t5_te or an H108N running 2.5.5_btmt1, and the web management interface is accessible (especially from WAN).
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 dataVendor should implement CSRF token validation (synchronizer token pattern) on all state-changing forms and AJAX endpoints. Users should avoid browsing untrusted sites while logged into router admin panels and disable remote WAN management if not required.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21729 — 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-2021-21729 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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