CVE-2018-19943
MediumExploitedPublic exploitIf exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code.
Published Oct 28, 2020 · Updated Aug 13, 2026
Key Facts
Patch immediately- CVE-2018-19943 is a medium-severity vulnerability (CVSS 5.4 v3.1) affecting QTS (Qnap).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 26, 2022 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 21% probability of exploitation in the next 30 days.
- Fixed versions are available, including QTS 4.2.6, QTS 4.3.3.1252, QTS 4.3.4.1282.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
5.4
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS (30-day exploit likelihood)
21%
Higher than 97.5% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2018-19943 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | May 24, 2022 | Jun 14, 2022 | Known |
| Industry KEV feed | Jan 26, 2022 | Jun 14, 2022 | Known |
| CIRCL KEV | May 24, 2022 | Jun 14, 2022 | Known |
| ENISA EUVD | May 24, 2022 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
12 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| QTSQnap | 4.2.6, 4.2.6-build_20170517, 4.2.6-build_20190322, 4.2.6-build_20190730, 4.2.6-build_20190921, 4.2.6-build_20191107, 4.2.6-build_20200109, 4.2.6-build_20200421 | 4.2.6 |
Patched Releases
QTS
4.2.6, 4.3.3.1252, 4.3.4.1282, 4.3.6.1263, 4.4.1.1261, 4.4.2.1270
Timeline
Publicly disclosed
Oct 28, 2020
Added to Industry KEV feed
Jan 26, 2022
Added to CISA KEV
May 24, 2022
Added to CIRCL KEV
May 24, 2022
Added to ENISA EUVD
May 24, 2022
Last updated
Aug 13, 2026
Weakness Type
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CWE-80 Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
References
FAQ
Common Questions.
If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code.
Affected: QTS (Qnap) versions 4.2.6, 4.2.6-build_20170517, 4.2.6-build_20190322, 4.2.6-build_20190730, 4.2.6-build_20190921, 4.2.6-build_20191107, 4.2.6-build_20200109, 4.2.6-build_20200421. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 26, 2022 and is known to be used in ransomware campaigns.
Yes. It was added on May 24, 2022 with a federal remediation due date of Jun 14, 2022.
Public exploit code is available.
Fixed versions are available, including QTS 4.2.6, QTS 4.3.3.1252, QTS 4.3.4.1282.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2018-19943 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo