CVE-2021-21749
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 · uneditedZTE MF971R product has two stack-based buffer overflow vulnerabilities. An attacker could exploit the vulnerabilities to execute arbitrary code.
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 MF971R mobile hotspot contains two stack-based buffer overflow vulnerabilities. Stack-based buffer overflows occur when data written to a stack buffer exceeds its allocated size, overwriting adjacent memory including return addresses, enabling attackers to redirect execution flow and execute arbitrary code.
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= v1.0.0b05= 1v1.0.0b06= 2v1.0.0b03= s2v1.0.0b03= sv1.0.0b05CVSS 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 device modelAccess the device admin interface or check the device label to confirm the model is ZTE MF971RAffected if Device model is not ZTE MF971R (not affected)
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Determine firmware versionLog into the device web management interface (typically 192.168.0.1 or 192.168.1.1) and navigate to Settings > Device Info or Status page to view the firmware version stringAffected if Unable to retrieve firmware version from device interface
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Compare against affected versionsCompare the installed firmware version string to the affected list: v1.0.0b05, 1v1.0.0b06, 2v1.0.0b03, s2v1.0.0b03, sv1.0.0b05Affected if Firmware version exactly matches any version in the affected list (v1.0.0b05, 1v1.0.0b06, 2v1.0.0b03, s2v1.0.0b03, or sv1.0.0b05)
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Check for firmware update availabilityVisit ZTE support site or check device admin interface for firmware update options; if current version matches affected list and no update is offered, vulnerability is presentAffected if Device runs affected firmware and vendor has not released a patched version
User is affected if the ZTE MF971R device is running firmware version v1.0.0b05, 1v1.0.0b06, 2v1.0.0b03, s2v1.0.0b03, or sv1.0.0b05.
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 firmware updates when available; until then, minimize attack surface by restricting network access to the device and monitoring for exploitation attempts.
- Consultation4.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21749 — 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-2021-21749 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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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
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