KEV Intelligence

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2023-6549

NetScaler ADC Denial of Service

Cloud Software Group / NetScaler ADC · affected before 12.35

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Severity
CVSS 8.2 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
57.6%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-6549 is an unauthenticated vulnerability affecting Cloud Software Group NetScaler ADC. Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

Cloud Software Group / NetScaler ADC affected before 12.35.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

NetScaler ADC Denial of Service

Improper Restriction of Operations within the Bounds of a Memory Buffer in NetScaler ADC and NetScaler Gateway allows Unauthenticated Denial of Service and Out-Of-Bounds Memory Read

Vendor Product Affected Status
Cloud Software Group NetScaler ADC Before 12.35 Affected
Cloud Software Group NetScaler ADC Before 51.15 Affected
Cloud Software Group NetScaler ADC Before 92.21 Affected
Cloud Software Group NetScaler ADC Before 37.176 Affected
Cloud Software Group NetScaler ADC Before 55.302 Affected
Cloud Software Group NetScaler ADC Before 55.302 Affected
Published
17 Jan 2024
Exploitation Reported
17 Jan 2024
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

nessus_scanner cisa nuclei_scanner

CVE References

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

Recorded 17 Jan 2024

Independent exploitation attestation added to the KEV Intelligence record.

Proof of concept available

Nuclei Templates

Recorded 12 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source Added
CISA First 2024-01-17 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.

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
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-6549.yaml 01 Jun 2026
Nessus https://www.tenable.com/plugins/nessus/189070 02 Jun 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS

57.6%

Weaknesses

Improper Restriction of Operations within the Bounds of a Memory Buffer CWE-119

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Citrix Netscaler ADC & Gateway - Out-Of-Bounds Memory Read

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. Public PoC available

    Public proof-of-concept code published

  2. Nuclei template available

    Scanner coverage available

  3. Nessus plugin available

    Scanner coverage available

  4. CVE published

    Vulnerability disclosed publicly

  5. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  6. 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.

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  • 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-2023-6549

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2023-6549",
  "confidence": "Confirmed",
  "cvss_score": 8.2,
  "cvss_estimated": false,
  "epss_score": 0.57633,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

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