CVE-2018-19943 QNAP NAS File Station Cross-Site Scripting Vulnerability
A cross-site scripting vulnerability affecting QNAP NAS File Station could allow remote attackers to inject malicious code.
From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.
Should You Worry?
- CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 24 May 2022.
- CISA lists it as known to be used in ransomware campaigns.
- Rated High severity (CVSS 8.0, scored by Vendor).
- It has been in the catalogue for 1,627 days. Systems still unpatched now have almost certainly been scanned for it.
What It Is
If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code. QNAP has already fixed these issues in the following QTS versions. QTS 4.4.2.1270 build 20200410 and later QTS 4.4.1.1261 build 20200330 and later QTS 4.3.6.1263 build 20200330 and later QTS 4.3.4.1282 build 20200408 and later QTS 4.3.3.1252 build 20200409 and later QTS 4.2.6 build 20200421 and later
Affected Versions
| Product | Versions |
|---|---|
| QNAP Systems Inc. QTS | unspecified to before 4.4.2.1270 |
| QNAP Systems Inc. QTS | unspecified to before 4.4.1.1261 unspecified to before 4.3.6.1263 |
| QNAP Systems Inc. QTS | unspecified to before 4.3.4.1282 |
| QNAP Systems Inc. QTS | unspecified to before 4.3.3.1252 |
| QNAP Systems Inc. QTS | unspecified to before 4.2.6 |
From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.
What To Do Now
- 1
Find it
Search your asset inventory and external attack surface for QNAP Network Attached Storage (NAS). Include cloud images, appliances and anything a supplier runs for you.
Attack Surface Management - 2
- 3
Hunt for compromise
If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.
Incident Response - 4
Prove it is fixed
Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.
Penetration Testing
Vendor Advisories
The Compliance Clock
General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.
Not Sure If You Are Exposed?
Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2018-19943 and every other exploited flaw on the list.