How severe is CVE-2018-19953?

CVE-2018-19953 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2018-19953?

Affected package information for CVE-2018-19953 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2018-19953?

No fixed version has been published for CVE-2018-19953 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2018-19953 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2018-19953, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2018-19953?

CVE-2018-19953 has an EPSS (Exploit Prediction Scoring System) score of 31.5%, placing it in the 97th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

Is CVE-2018-19953 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2018-19953 (QNAP NAS File Station Cross-Site Scripting Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-05-24. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-06-14. The required action was: Apply updates per vendor instructions. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2018-19953?

CVE-2018-19953 is classified as Cross-site Scripting (XSS) (CWE-79), CWE-80 (CWE-80). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2018-19953?

CVE-2018-19953 affects qnap qts (1 version, e.g. 4.2.6). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2018-19953 published, and has it been updated?

CVE-2018-19953 was published on October 28, 2020 and was last updated on November 3, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2022-05-24 — agencies required to remediate by 2022-06-14 · Ransomware

CVE-2018-19953

MEDIUM

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…

Published

Oct 28, 2020

Updated

Nov 3, 2025

Affected

0 pkgs

Patched

None yet

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

31.5%probability of exploitation in next 30 days

Moderate Risk97th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

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.

Affected Products

1 product · 12 configurations

qtsqnap

≥ 4.4.2 && < 4.4.2.1231

1 version

4.2.6

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

If exploited, this cross-site scripting vulnerability could allow remote…

twitter.comAPIJun 2020

If exploited, this cross-site scripting vulnerability could allow remote…

cisa.govCISAMay 2022

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2018-19953 in your stack?

O3 detects CVE-2018-19953 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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