Is CVE-2018-19953 actively exploited?

Yes. KEV Intelligence tracks CVE-2018-19953 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2018-19953. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2018-19953 affects QNAP Systems Inc. QTS. KEV Intelligence lists 6 version rows; examples include unspecified to < 4.4.2.1231, unspecified to < 4.4.1.1201, and unspecified to < 4.3.6.1218.

Yes. CVE-2018-19953 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2018-19953

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2018-19953 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

QTS Cross-Site Scripting

QNAP Systems Inc. / QTS · affected before 4.4.2.1231

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Severity: CVSS 6.1 · Medium
Confidence: Confirmed
Exploit status: Exploited in the wild
EPSS: 23.9%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2018-19953 is an unauthenticated vulnerability affecting QNAP Systems Inc. QTS. If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code. QNAP has already fixed...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

QNAP Systems Inc. / QTS affected before 4.4.2.1231.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code

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.

Vendor Product Affected Status

QNAP Systems Inc. QTS Before 4.4.2.1231 Affected

QNAP Systems Inc. QTS Before 4.4.1.1201 Affected

QNAP Systems Inc. QTS Before 4.3.6.1218 Affected

QNAP Systems Inc. QTS Before 4.3.4.1190 Affected

QNAP Systems Inc. QTS Before 4.3.3.1161 Affected

QNAP Systems Inc. QTS Before 4.2.6 Affected

Published: 28 Oct 2020
Exploitation Reported: 24 May 2022
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: Required

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2018-19953
qnap.com/zh-tw/security-advisory/qsa-20-01 qnap.com · CVE Record https://www.qnap.com/zh-tw/security-advisory/qsa-20-01

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 24 May 2022

Independent exploitation attestation added to the KEV Intelligence record.

Used in malware

CISA

Recorded 24 May 2022

Malware families have been linked to exploitation of this CVE.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source	Added
CISA First	2022-05-24 00:00 UTC
CVE	2026-08-13 04:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

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No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

6.1 Medium

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

EPSS

23.9%

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE-79 Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) CWE-80

All CVSS Scores

CVSS v3.1 6.1 Medium

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

CVSS v2.0 4.3 Medium

AV:N/AC:M/Au:N/C:N/I:P/A:N

Timeline

From disclosure to observed exploitation

13 Aug 2026
KEV confirmed by CVE

Exploitation attested by an external source
24 May 2022
Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
24 May 2022
First public exploitation report

Exploit observed in malware
28 Oct 2020
CVE published

Vulnerability disclosed publicly
07 Dec 2018
CVE ID reserved

Identifier reserved by the CNA

Pro API

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2018-19953

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2018-19953",
  "confidence": "Confirmed",
  "cvss_score": 6.1,
  "cvss_estimated": false,
  "epss_score": 0.23894,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

Early warning alerts

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