Threats / Zyxel / CVE-2023-27992
CVE-2023-27992
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Zyxel Multiple Network-Attached Storage (NAS) Devices vulnerability
Zyxel NAS devices contain a pre-authentication command injection vulnerability allowing unauthenticated remote code execution via crafted HTTP requests.
Verdict
Today item — known-exploited.
An unauthenticated attacker can execute arbitrary commands on vulnerable Zyxel NAS devices without authentication, leading to complete system compromise. The high EPSS score and active exploitation in the wild indicate immediate risk.
CISA KEV Yes · 2023-06-235EPSS 0.84195 (verify live)6CVSS 9.83CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
8 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-23).
Probability (EPSS)
EPSS 0.84195 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) · Affected: Zyxel, Multiple Network-Attached Storage (NAS) Devices. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-78 OS Command Injection — weakness family: Injection.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 4 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious HTTP request containing shell metacharacters to inject commands into a vulnerable Zyxel NAS endpoint.
Business
Attackers gain unauthenticated code execution on network storage infrastructure, enabling data theft, encryption, or lateral movement.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute system commands with the privileges of the NAS service process to enumerate the device and connected network.
Business
Compromised NAS devices become pivot points for attacking other network resources and accessing sensitive stored data.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent access by installing backdoors or modifying system configurations on the compromised device.
Business
Long-term unauthorized access to centralized storage enables sustained data exfiltration and operational disruption.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05