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CVE-2023-6549

HIGH
7.5
CVSS Score
Published: January 17, 2024 at 08:15 PM UTC
Updated: June 17, 2026 at 06:50 AM UTC
3 products affected across 2 vendorsNetScaler GatewayNetscaler Application Delivery ControllerNetScaler ADC

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Severity
HIGH7.5
Exploitation
CISA KEV
Exploit prediction
EPSS 58%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score57.6%

EPSS (Exploit Prediction Scoring System) estimates a 57.6% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for a denial-of-service when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

Required Action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Ransomware Use
Unknown
Added to KEV
Jan 17, 2024
Remediation Due
Feb 7, 2024
992 days overdue
Notes
https://support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549
https://nvd.nist.gov/vuln/detail/CVE-2023-6549

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netscaler Application Delivery Controller· Citrix
95%
12.1 ≤ v < 12.1-55.30213.0 ≤ v < 13.0-92.2113.1 ≤ v < 13.1-37.17613.1 ≤ v < 13.1-51.1514.1 ≤ v < 14.1-12.35
Affected range stops below 12.1-55.302, so it looks safe — our inference, not a vendor statement
Affected range stops below 13.0-92.21, so it looks safe — our inference, not a vendor statement
Affected range stops below 13.1-37.176, so it looks safe — our inference, not a vendor statement
Affected range stops below 13.1-51.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 14.1-12.35, so it looks safe — our inference, not a vendor statement
NetScaler Gateway· Citrix
95%
13.0 ≤ v < 13.0-92.2113.1 ≤ v < 13.1-51.1514.1 ≤ v < 14.1-12.35
Affected range stops below 13.0-92.21, so it looks safe — our inference, not a vendor statement
Affected range stops below 13.1-51.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 14.1-12.35, so it looks safe — our inference, not a vendor statement
NetScaler ADC· Cloud
60%
12.1-FIPS ≤ v < 55.30212.1-NDcPP ≤ v < 55.30213.0 ≤ v < 92.2113.1 ≤ v < 51.1513.1-FIPS ≤ v < 37.17614.1 ≤ v < 12.3512.1-FIPS12.1-NDcPP13.013.113.1-FIPS14.1
Affected range stops below 12.35, so it looks safe — our inference, not a vendor statement
Affected range stops below 37.176, so it looks safe — our inference, not a vendor statement
Affected range stops below 51.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 55.302, so it looks safe — our inference, not a vendor statement
Affected range stops below 92.21, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Vendor Advisory
Source: [email protected]
https://support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-6549

SSVC — Action Prioritization

SSVCActiveAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-119

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