A command injection vulnerability in the “show_zysync_server_contents” function of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and N…

published 2023-11-30 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-39168

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 40.0%; EPSS 40.0% chance of exploitation in 30 days, percentile 98%
public exploits: 0; none known

A command injection vulnerability in the “show_zysync_server_contents” function of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted HTTP POST request.

Patch / fix

links 1

zyxel.com/global/en/support/security-advisories/zyxel-security-advis… advisory

Exploit prediction

40.00% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Zyxel NAS326 firmware
Zyxel NAS542 firmware

Classification

Weakness

CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

zyxel.com /global/en/support/security-advisories/zyxel-security-advisory-for-authentication-bypass-and-command-injection
vendor-advisory, patch

Sources

CVE List CVE-2023-35138
NVD CVE-2023-35138

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary