Vulnerability · Published Oct 15, 2026 · Assigned by qnap
CVE-2026-39991Stored Cross-Site Scripting (XSS) in Note Station file upload functionality
Medium 4.8
In plain English
A medium-severity cross-site scripting in Notes Station 3 from QNAP Systems Inc.. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).
Severity (CVSS 4.0)4.8Medium
Exploit odds (30 days)0.3%top 78.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
A cross-site scripting (XSS) vulnerability has been reported to affect Notes Station 3. If a remote attacker gains a user account, they can then exploit the vulnerability to inject malicious code. We have already fixed the vulnerability in the following version: Notes Station 3 3.9.12 and later
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| QNAP Systems Inc. | Notes Station 3 | 3.9.x – before 3.9.12 |
Weakness: CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N