CVE-2023-27992

criticalpriority · act · 90OT risk · criticalKEV · exploitedEPSS 0.823 · 100 %ileEURUUS

grimoire priorityP0 · Act now

Exploitable?

Yes · in the wild

CISA KEV

Likely / severe?

82.3% (100th) EPSS

CVSS 9.8 · critical

Is it mine?

9 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

added 2023-06-23remediate by 2023-07-14

required action Apply updates per vendor instructions.

EPSS · scored 2026-10-27

Zyxel Multiple NAS Devices Command Injection Vulnerability

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.

cvss

Technical severity, 0–10. One row per scoring source.

9.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.19.8criticalAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · security@zyxel.com.twexploitability 3.9 · impact 5.9

v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Hsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: active · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-78USprimaryCWE-78US

affected products (9)

Products and version ranges known to be affected.

Zyxel NAS326 firmware≤ < V5.21(AAZF.14)C0enisa_euvdEU
Zyxel NAS540 firmware≤ < V5.21(AATB.11)C0enisa_euvdEU
Zyxel NAS542 firmware≤ < V5.21(ABAG.11)C0enisa_euvdEU
Zyxel Communications Corp. NAS326≤ 5.21(AAZF.14)C0fstec_bduRU
Zyxel Communications Corp. NAS540≤ 5.21(AATB.11)C0fstec_bduRU
Zyxel Communications Corp. NAS542≤ 5.21(ABAG.11)C0fstec_bduRU
zyxel nas326 firmware< 5.21\(aazf.14\)c0nvdUScpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*
zyxel nas540 firmware< 5.21\(aatb.11\)c0nvdUScpe:2.3:o:zyxel:nas540_firmware:*:*:*:*:*:*:*:*
zyxel nas542 firmware< 5.21\(abag.11\)c0nvdUScpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2023-06-19modified 2026-06-17

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references (5)

External citations — patches, advisories, analysis.

scry

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