CVE-2018-19945: Improper Limitation of a Pathname to a Restricted Directory in QTS

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-12-31 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability has been reported to affect earlier QNAP devices running QTS 4.3.4 to 4.3.6. Caused by improper limitations of a pathname to a restricted directory, this vulnerability allows for renaming arbitrary files on the target system, if exploited. QNAP have already fixed this vulnerability in the following versions: QTS 4.3.6.0895 build 20190328 (and later) QTS 4.3.4.0899 build 20190322 (and later) This issue does not affect QTS 4.4.x or QTS 4.5.x.

Affected products

QNAP QTS: from 4.3.4 before 4.3.4.0899; from 4.3.5 before 4.3.6.0895 — fixed in 4.3.4.0899, 4.3.6.0895

How to fix

Upgrade to a fixed version: QNAP QTS 4.3.4.0899, 4.3.6.0895. Check the vendor advisory for mitigations.

References

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