Cyber Resilience

CVE-2018-19949

RCE in Qnap Qts ≤ 4.2.6

CISA KEVActive ExploitationEUVD ExploitedRansomware-linkedRCECommand Injection
Published
28 October 2020
Modified
13 August 2026
KEV Added
24 May 2022
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.24 98th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2018-19949 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Qnap Qts. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2018-19949 is a command injection vulnerability stemming from improper input validation, tracked under CWEs 20, 77, and 78. It affects multiple versions of QNAP QTS network-attached storage firmware and carries a CVSS 3.1 base score of 9.8.

Unauthenticated remote attackers can exploit the flaw over the network to execute arbitrary operating-system commands, resulting in full compromise of confidentiality, integrity, and availability on the affected device.

QNAP has released fixes in 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, and 4.2.6 build 20200109, as detailed in security advisory QSA-20-01.

The vulnerability appears in the CISA Known Exploited Vulnerabilities catalog, confirming observed in-the-wild exploitation.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

If exploited, this command injection vulnerability could allow remote attackers to run arbitrary commands. 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;…

more

QTS 4.3.4.1190 on build 20200107; QTS 4.3.3.1161 on build 20200109; QTS 4.2.6 on build 20200109.

CWE(s)
KEV Date Added
24 May 2022

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
T1059.008 Network Device CLI Execution
Adversaries may abuse scripting or built-in command line interpreters (CLI) on network devices to execute malicious command and payloads.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2020-2509Same product: Qnap Qtsboth on KEV
CVE-2017-6360Same product: Qnap Qts
CVE-2017-6361Same product: Qnap Qts
CVE-2023-39300Same product: Qnap Qts
CVE-2025-22481Same product: Qnap Qts
CVE-2024-53692Same product: Qnap Qts
CVE-2024-21903Same product: Qnap Qts
CVE-2025-30264Same product: Qnap Qts
CVE-2024-38641Same product: Qnap Qts
CVE-2023-41281Same product: Qnap Qts

Affected Assets

qnap
qts
4.2.6 · ≤ 4.2.6 · 4.3.1.0013 — 4.3.3.1161 · 4.3.4 — 4.3.4.1190

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 6 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.2.3
  • V1.2.5
  • V1.2.8
  • V1.2.9

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-20 CWE-78

Directly implements checks on information inputs to reject invalid data before processing.

addresses: CWE-20

Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.

addresses: CWE-20

Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.

addresses: CWE-78

Platform-independent apps typically execute inside a managed runtime or sandbox that restricts direct OS command execution, reducing the ability to exploit OS command injection.

addresses: CWE-20

Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require and enforce input validation during development.

DE.CM-09 partial match
prevents

Runtime monitoring of software and data can detect anomalous command execution resulting from injection.

ID.RA-01 partial match
prevents

Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.

PR.PS-02 partial match
prevents

Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.

finds

Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.

prevents

Secure-coding guidelines and mandatory security testing (including code scans) compel developers to validate and sanitize inputs at design and implementation time, lowering the incidence of malformed or malicious data reaching downstream components.

prevents

Mandating input controls that include integrity checks and input validation ensures that untrusted data is examined before use, blocking the root cause of many injection and malformed-data weaknesses.

prevents

Security-by-design principles explicitly call for data validation and sanitization at every layer, reducing the chance that malformed or malicious input will be processed without scrutiny.

none

Environment separation limits the blast radius of an exploited command injection but does not prevent the flaw itself.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

RHEL 8 (1 rule)
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-20

References