What is CVE-2021-34355?

CVE-2021-34355 is a high-severity vulnerability in QNAP Nas, classified under Cross-site Scripting. CVSS score: 7.6/10. Published 2021-10-01.

How severe is CVE-2021-34355?

High severity. CVSS v3 base score is 7.6 out of 10.

XSS in QNAP Nas

CVE-2021-34355

A cross-site scripting (XSS) vulnerability has been reported to affect QNAP NAS running Photo Station. If exploited, this vulnerability allows remote attackers to inject malicious code. We have already fixed this vulnerability in the following versions of Photo Station: Photo Station 5.4.10 ( 2021/08/19 ) and later Photo Station 5.7.13 ( 2021/08/19 ) and later Photo Station 6.0.18 ( 2021/09/01 ) and later

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-10-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (49.0th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

QNAP Nas
QNAP Photo Station
QNAP Systems Inc. Photo Station — versions unspecified

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.qnap.com/en/security-advisory/qsa-21-42 (Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2021-34355?: CVE-2021-34355 is a high-severity vulnerability in QNAP Nas, classified under Cross-site Scripting. CVSS score: 7.6/10. Published 2021-10-01.
How severe is CVE-2021-34355?: High severity. CVSS v3 base score is 7.6 out of 10.