What is CVE-2021-34344?

CVE-2021-34344 is a critical-severity vulnerability in QNAP Qts, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2021-09-10.

How severe is CVE-2021-34344?

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

Buffer overflow in QNAP Qts

CVE-2021-34344

A stack buffer overflow vulnerability has been reported to affect QNAP device running QUSBCam2. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of QUSBCam2: QTS 4.5.4: QUSBCam2 1.1.4 ( 2021/07/30 ) and later QTS 5.0: QUSBCam2 2.0.1 ( 2021/08/03 ) and later QTS 4.3.6: QUSBCam2 1.1.4 ( 2021/07/30 ) and later QTS 4.3.3: QUSBCam2 1.1.4 ( 2021/08/06 ) and later QuTS hero 4.5.3: QUSBCam2 1.1.4 ( 2021/07/30 ) and later

Vulnerability class: Buffer Overflow

Published 2021-09-10 · 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: 0.016 (74.5th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 75th percentile — 74.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.016 · newest: 0.016 · change: 0.000

Affected products

QNAP Qts — versions 4.3.6, 4.5.4
QNAP Qusbcam2
QNAP Quts Hero — versions h4.5.3
QNAP Systems Inc. Qusbcam2 — versions unspecified

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

www.qnap.com/en/security-advisory/qsa-21-34 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-34344?: CVE-2021-34344 is a critical-severity vulnerability in QNAP Qts, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2021-09-10.
How severe is CVE-2021-34344?: Critical severity. CVSS v3 base score is 9.8 out of 10.