What it is
CVE-2023-27992 is an unauthenticated vulnerability affecting Zyxel NAS326 firmware and 2 other products. The pre-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior...
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2023-27992
NAS326 firmware Command Injection
Zyxel / NAS326 firmware · affected before V5.21(AAZF.14)C0
- Severity
- CVSS 9.8 · Critical
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 84.2%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
Zyxel / NAS326 firmware affected before v5.21(aazf.14)c0.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
NAS326 firmware Command Injection
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.
Vendor
Product
Affected
Status
Zyxel
NAS326 firmware
Before V5.21(AAZF.14)C0
Affected
Zyxel
NAS540 firmware
Before V5.21(AATB.11)C0
Affected
Zyxel
NAS542 firmware
Before V5.21(ABAG.11)C0
Affected
- Published
- 19 Jun 2023
- Exploitation Reported
- 23 Jun 2023
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
edge
cisa
nessus_scanner
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-27992
- zyxel.com/global/en/support/security-advisories/zyxel-... zyxel.com · CVE Record https://www.zyxel.com/global/en/support/security-advisories/zyxel-sec...
Exploitation evidence
Why KEV Intelligence marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CISA
Independent exploitation attestation added to the KEV Intelligence record.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2023-06-23 00:00 UTC |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
Nessus template detected 02 Jun 2025.
View Nessus template (opens in new tab)Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →Scanner Artifacts
Scanner and exploit-framework references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nessus | https://www.tenable.com/plugins/nessus/200304 | 02 Jun 2025 |
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
9.8
Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
84.2%
Timeline
From disclosure to observed exploitation
-
Nessus plugin available
Scanner coverage available
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2023-27992
Free JSON includes basic KEV fields{
"cve_id": "CVE-2023-27992",
"confidence": "Confirmed",
"cvss_score": 9.8,
"cvss_estimated": false,
"epss_score": 0.84195,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.