CVE-2023-27992
Zyxel Multiple NAS Devices Command Injection Vulnerability
- Critical 9.8
- Exploited: added to CISA KEV 23 Jun 2023
Description
The pre-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior to V5.21(AAZF.14)C0, NAS540 firmware versions prior to V5.21(AATB.11)C0, and NAS542 firmware versions prior to V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands remotely by sending a crafted HTTP request.
Key facts
- Published
- 19 Jun 2023
- Last changed
- 21 Oct 2025
- Assigned by
- Zyxel
- KEV added
- 23 Jun 2023
- KEV fix due
- 14 Jul 2023
- EPSS
- 82.264% likely to be exploited in the next 30 days, higher than 99.667% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: yes; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 9.8CVSS 3.1, Criticalfrom the CNA (Zyxel)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
What to do
- Apply updates per vendor instructions.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Zyxel | NAS326 firmware |
|
| Zyxel | NAS540 firmware |
|
| Zyxel | NAS542 firmware |
|
Timeline
- 19 Jun 2023 Published
- 23 Jun 2023 CVE-2023-27992 added to CISA KEV
- 23 Jun 2023 Added to the CISA KEV catalogue
Weakness
Practice this bug class
HackZoneLabs has a hands-on lab on OS command injection (CWE-78).