What is CVE-2021-34351?

CVE-2021-34351 is a critical-severity vulnerability in QNAP Qvr, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-09-27.

How severe is CVE-2021-34351?

Critical severity. CVSS v3 base score is 9.8 out of 10.

RCE in QNAP Qvr

CVE-2021-34351

A command injection vulnerability has been reported to affect QNAP device running QVR. If exploited, this vulnerability could allow remote attackers to run arbitrary commands. We have already fixed this vulnerability in the following versions of QVR: QVR 5.1.5 build 20210803 and later

Vulnerability class: Command Injection (OS Command Injection)

Published 2021-09-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.015 (72.7th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000

Affected products

QNAP Qvr
QNAP Systems Inc. Qvr — versions unspecified

Weakness classification (CWE)

References

www.qnap.com/en/security-advisory/qsa-21-35 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-34351?: CVE-2021-34351 is a critical-severity vulnerability in QNAP Qvr, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-09-27.
How severe is CVE-2021-34351?: Critical severity. CVSS v3 base score is 9.8 out of 10.