What it is
CVE-2023-0656 is an unauthenticated vulnerability affecting SonicWall SonicOS. A Stack-based buffer overflow vulnerability in the SonicOS allows a remote unauthenticated attacker to cause Denial of Service (DoS),...
Vulnerability report
Exploited in the wild
High confidence
Not in CISA KEV
CVE-2023-0656
SonicOS Denial of Service
SonicWall / SonicOS · SonicOS NSv 6.5.4.4-44v-21-1551 and earlier
- Severity
- CVSS 7.5 · High
- Confidence
- High
- Exploit status
- Exploited in the wild
- EPSS
- 41.3%
- 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 high.
Who is affected?
SonicWall / SonicOS sonicos nsv 6.5.4.4-44v-21-1551 and earlier.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
SonicOS Denial of Service
A Stack-based buffer overflow vulnerability in the SonicOS allows a remote unauthenticated attacker to cause Denial of Service (DoS), which could cause an impacted firewall to crash.
Vendor
Product
Affected
Status
SonicWall
SonicOS
SonicOS NSv 6.5.4.4-44v-21-1551 and earlier
Affected
SonicWall
SonicOS
SonicOS NSsp 7.0.1-5083 and earlier
Affected
SonicWall
SonicOS
SonicOS 7.0.1-5095 and earlier
Affected
- Published
- 02 Mar 2023
- Exploitation Reported
- 22 Apr 2025
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
edge
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-0656
- psirt.global.sonicwall.com/vuln-detail/SNWLID-2023-0004 psirt.global.sonicwall.com · CVE Record https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2023-0004
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
The Shadowserver
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 |
|---|---|
| The Shadowserver First | 2025-04-28 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
No scanner integrations recorded yet.
Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →No detection artifacts or sensor request patterns are available for this CVE yet.
Check back as sensor telemetry and scanner integrations are updated.
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
7.5
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
41.3%
Weaknesses
Timeline
From disclosure to observed exploitation
-
Added to KEV Intelligence KEV Feed
High-confidence, third-party attested exploitation
-
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-2023-0656
Free JSON includes basic KEV fields{
"cve_id": "CVE-2023-0656",
"confidence": "High",
"cvss_score": 7.5,
"cvss_estimated": false,
"epss_score": 0.41319,
"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.