What is CVE-2022-34747?

CVE-2022-34747 is a critical-severity vulnerability in Zyxel Nas326, classified under Use of Externally-Controlled Format String. CVSS score: 9.8/10. Published 2022-09-06.

How severe is CVE-2022-34747?

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

Is CVE-2022-34747 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Zyxel Nas326

CVE-2022-34747

A format string vulnerability in Zyxel NAS326 firmware versions prior to V5.21(AAZF.12)C0 could allow an attacker to achieve unauthorized remote code execution via a crafted UDP packet.

Published 2022-09-06 · 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: 0.017 (76.9th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.9% 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: 0.017 · change: +0.002

Affected products

Zyxel Nas326
Zyxel Nas326 Firmware
Zyxel Nas326 Firmware — versions < V5.21(AAZF.12)C0

Weakness classification (CWE)

CWE-134 — Use of Externally-Controlled Format String

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

www.zyxel.com/support/Zyxel-security-advisory-for-format-string-vulnerability-i… (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2022-34747?: CVE-2022-34747 is a critical-severity vulnerability in Zyxel Nas326, classified under Use of Externally-Controlled Format String. CVSS score: 9.8/10. Published 2022-09-06.
How severe is CVE-2022-34747?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2022-34747 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.