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CVE-2023-6549

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow

8.2 HIGHActively exploited (CISA KEV)EPSS 57.6%
  1. Published17 Jan 2024
  2. Added to CISA KEV17 Jan 2024
  3. Remediation due7 Feb 2024
Actively exploited (CISA KEV)

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.

Added to KEV: 17 Jan 2024Federal remediation due: 7 Feb 2024

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

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected products

Citrix NetScaler Application Delivery Controller≥ 13.0 < 13.0-92.21 · ≥ 13.1 < 13.1-51.15 · ≥ 14.1 < 14.1-12.35 · ≥ 12.1 < 12.1-55.302
Citrix NetScaler Gateway≥ 13.0 < 13.0-92.21 · ≥ 13.1 < 13.1-51.15 · ≥ 14.1 < 14.1-12.35

Remediation

Fixed in
Citrix NetScaler Application Delivery Controller≥ 13.0-92.21
Citrix NetScaler Gateway≥ 13.0-92.21

References

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Frequently asked

Is CVE-2023-6549 being actively exploited?

Yes. CVE-2023-6549 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 17 Jan 2024.

How severe is CVE-2023-6549?

CVE-2023-6549 has a CVSS 3.1 base score of 8.2, rated high. EPSS estimates a 57.6% probability of exploitation.

Which products are affected by CVE-2023-6549?

Affected products include Citrix NetScaler Application Delivery Controller, Citrix NetScaler Gateway.

How do I fix CVE-2023-6549?

Upgrade affected software to a fixed version, for example Citrix NetScaler Application Delivery Controller 13.0-92.21, Citrix NetScaler Gateway 13.0-92.21 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2023-6549 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.