CVE-2023-27992

Exp

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.

Published: 2023-06-19 Last update: 2025-10-27 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-27992 is rated Critical Active Threat (99.8/100): CVSS Critical severity, with high exploitation likelihood (EPSS 86.53%, 99th percentile). CISA KEV confirms active exploitation (added 2023-06-23) affecting Zyxel / Multiple Network-Attached Storage (NAS) Devices. a weakness (CWE-78) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2023-27992

Name: Zyxel Multiple NAS Devices Command Injection Vulnerability · CISA KEV detail

Exploit added: 2023-06-23

Action due: 2023-07-14

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2023-27992

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-02-11 85.69% 86.53% +0.84%
2 2026-02-07 84.01% 85.69% +1.69%
3 2025-11-21 — 84.01% —

Full EPSS history (30 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-27992

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2023-27992

Affected software / configurations for CVE-2023-27992

Vendor Product Version Raw CPE
zyxel nas326_firmware < 5.21\(aazf.14\)c0 cpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*
zyxel nas540_firmware < 5.21\(aatb.11\)c0 cpe:2.3:o:zyxel:nas540_firmware:*:*:*:*:*:*:*:*
zyxel nas542_firmware < 5.21\(abag.11\)c0 cpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

References for CVE-2023-27992

cvelogic Threat Intelligence