Medium severity · published Oct 15, 2026
CVE-2026-39991
Stored Cross-Site Scripting (XSS) in Note Station file upload functionality
4.8
CVSS
0.3%
EPSS
No
On KEV
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
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NS
Notes Station 3 · QNAP Systems Inc.
3.9.x before 3.9.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39991
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39991
www.qnap.com
https://www.qnap.com/en/app-release-notes?keyword=Notes%20Station%203&app=NotesStation3&product-line=nas
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