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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 14 Jun 2022. Known ransomware use
QtsOperating system · Qnap

CVE-2018-19953

MEDIUM · 6.1 CVSS v3.1 Published 2020-10-28
Fix available
A fix is available. Upgrade to 4.2.6 / 4.3.3.1161 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware Remotely reachable No privileges

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 · unedited
If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code. QNAP has already fixed the issue in the following QTS versions. QTS 4.4.2.1231 on build 20200302; QTS 4.4.1.1201 on build 20200130; QTS 4.3.6.1218 on build 20200214; QTS 4.3.4.1190 on build 20200107; QTS 4.3.3.1161 on build 20200109; QTS 4.2.6 on build 20200109.

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 confidence

Cross-site scripting (XSS) vulnerability in QNAP QTS firmware that allows remote attackers to inject malicious scripts through unspecified vectors. The vulnerability is exploitable without authentication and could lead to session hijacking or malicious content injection against users of the QTS web interface.

MitigationUpdate QNAP QTS to one of the fixed versions (QTS 4.4.2.1231 build 20200302, 4.4.1.1201 build 20200130, 4.3.6.1218 build 20200214, 4.3.4.1190 build 20200107, 4.3.3.1161 build 20200109, or 4.2.6 build 20200109) as specified in the vendor advisory.

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
QtsOperating system
Affected:< 4.2.6>= 4.3.1.0013, < 4.3.3.1161>= 4.3.4, < 4.3.4.1190>= 4.3.6, < 4.3.6.1218>= 4.4.0, < 4.4.1.1201>= 4.4.2, < 4.4.2.1231= 4.2.6

CVSS 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
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify QNAP device and access QTS version
    Log into the QTS web interface as an administrator. Navigate to Control Panel > System > System Information, or use the Qfinder Pro tool to locate the device and retrieve its firmware version.
    Affected if The displayed QTS version falls within any of these ranges: < 4.2.6, = 4.2.6, >= 4.3.1.0013 to < 4.3.3.1161, >= 4.3.4 to < 4.3.4.1190, >= 4.3.6 to < 4.3.6.1218, >= 4.4.0 to < 4.4.1.1201, or >= 4.4.2 to < 4.4.2.1231.
  2. Check QTS version via command line
    If you have SSH access to the NAS, connect and run the command 'version' or 'cat /etc/version' to retrieve the exact QTS firmware build and version number.
    Affected if The version output matches any of the affected version ranges listed above.
  3. Verify web interface is accessible
    Confirm the QTS web administration interface is reachable over HTTPS/HTTP on the standard ports (8080 or 443). This vulnerability affects the web interface itself.
    Affected if The QTS web interface is accessible and the version is within the affected ranges, meaning unauthenticated remote attackers could potentially inject malicious scripts.

A QNAP NAS running QTS firmware version within the affected ranges listed above, with the web interface exposed, is vulnerable to unauthenticated XSS attacks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 4.2.6 / 4.3.3.1161 / 4.3.4.1190 or later
Fixed in 4.2.64.3.3.11614.3.4.1190
Interim mitigation

Update QNAP QTS to one of the fixed versions (QTS 4.4.2.1231 build 20200302, 4.4.1.1201 build 20200130, 4.3.6.1218 build 20200214, 4.3.4.1190 build 20200107, 4.3.3.1161 build 20200109, or 4.2.6 build 20200109) as specified in the vendor advisory.

Recommended fix High confidence

QTS 4.2.6 (build 20200109), 4.3.3.1161 (build 20200109), 4.3.4.1190 (build 20200107), 4.3.6.1218 (build 20200214), or newer branches 4.4.1.1201/4.4.2.1231

  1. 1. Identify the current QTS version by logging into the QNAP NAS web interface and checking System Administration > Firmware version.
  2. 2. Determine which branch of QTS is currently installed (4.2.x, 4.3.3.x, 4.3.4.x, or 4.3.6.x).
  3. 3. Based on the current version branch, upgrade to the corresponding fixed version: For 4.2.x branch, upgrade to QTS 4.2.6 (build 20200109); For 4.3.3.x branch, upgrade to QTS 4.3.3.1161 (build 20200109); For 4.3.4.x branch, upgrade to QTS 4.3.4.1190 (build 20200107); For 4.3.6.x branch, upgrade to QTS 4.3.6.1218 (build 20200214); Alternatively, upgrade to QTS 4.4.1.1201 or 4.4.2.1231 for the late
  4. 4. Before upgrading, back up all critical data and configurations.
  5. 5. Download the firmware update from the QNAP download center and apply via Control Panel > Firmware Update > Firmware Update - either via manual upload or automatic update check.
Caveat Review QNAP release notes before upgrading; some legacy apps or configurations may require updates after major version jumps

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Qts Exploited in the wild — priority engagement
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-19953 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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