CVE-2021-28798
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 relative path traversal vulnerability has been reported to affect QNAP NAS running QTS and QuTS hero. If exploited, this vulnerability allows attackers to modify files that impact system integrity. QNAP have already fixed this vulnerability in the following versions: QTS 4.5.2.1630 Build 20210406 and later QTS 4.3.6.1663 Build 20210504 and later QTS 4.3.3.1624 Build 20210416 and later QuTS hero h4.5.2.1638 Build 20210414 and later QNAP NAS running QTS 4.5.3 are not affected.
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 relative path traversal vulnerability in QNAP NAS devices running QTS and QuTS hero allows attackers to modify files on the system by using '..' sequences in file paths, potentially compromising system integrity. The vulnerability stems from insufficient input validation in the web interface or API endpoints.
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>= 4.3.2.0144, < 4.3.3.1624>= 4.3.4.0000, < 4.3.6.1663>= 4.4.0000, < 4.5.2.1630< h4.5.2.1638CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.
-
Identify the QNAP operating systemLog into the NAS admin interface and check the dashboard or system information page to confirm whether the device runs QTS or QuTS heroAffected if The device runs QTS or QuTS hero - other QNAP OS variants are not affected by this CVE
-
Check the installed QTS versionIn the QTS admin panel, go to Control Panel > System > Firmware Update > Firmware Information, or use the command 'getcfg System.Version' via SSHAffected if The version is 4.3.2.0144 through 4.3.3.1623, or 4.3.4.0000 through 4.3.6.1662, or 4.4.0000 through 4.5.2.1629
-
Check the installed QuTS hero versionIn the QuTS hero admin panel, navigate to Control Panel > System > Firmware Update > Firmware Information to view the build number and versionAffected if The version is any build before h4.5.2.1638
-
Verify web interface or API accessibilityConfirm that the QNAP web administration interface (ports 8080 or 443) or the API endpoints are accessible from the networkAffected if The web interface or API is exposed to the network without proper access controls, enabling the path traversal attack vector
The system is affected if it runs QTS in any of the three vulnerable version ranges or QuTS hero below h4.5.2.1638, AND the web interface or API is network-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 data4.3.3.16244.3.6.16634.5.2.1630
Update the QNAP NAS firmware to one of the patched versions: QTS 4.5.2.1630 (Build 20210406)+, QTS 4.3.6.1663 (Build 20210504)+, QTS 4.3.3.1624 (Build 20210416)+, or QuTS hero h4.5.2.1638 (Build 20210414)+.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 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 $2,512.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-28798 — 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-2021-28798 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