CVE-2023-6549Known exploitationNetwork attack vector

Unauthenticated service disruption via out-of-bounds memory access

Published Jan 17, 2024 · Updated Oct 21, 2025

Memory-buffer bounds errors in Cloud Software Group NetScaler ADC allow remote attackers to interrupt service and read memory. The vendor identifies an out-of-bounds memory operation but has not published the affected request parser, input field, or exact malformed operation. Exploitation requires a customer-managed appliance configured as a Gateway or AAA virtual server; ordinary load-balancing configurations and managed cloud services are outside the reported affected state.

CVSS severity8.2
High
EPSS probability57.63%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory-buffer bounds errors in Cloud Software Group NetScaler ADC allow remote attackers to interrupt service and read memory. The vendor identifies an out-of-bounds memory operation but has not published the affected request parser, input field, or exact malformed operation. Exploitation requires a customer-managed appliance configured as a Gateway or AAA virtual server; ordinary load-balancing configurations and managed cloud services are outside the reported affected state.

The record

CVE
CVE-2023-6549
Published
Jan 17, 2024
Updated
Oct 21, 2025
Vendor
Cloud Software Group
Product
NetScaler ADC
Classifications
CWE-119, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 17, 2024Exploitation reportedCISA Known Exploited Vulnerabilities listing
  2. Jan 17, 2024CVE publishedPublication date reported by the CVE source.
  3. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.1-FIPS <55.302
  2. Affected versionversion=12.1-NDcPP <55.302
  3. Affected versionversion=13.0 <92.21
  4. Affected versionversion=13.1 <51.15
  5. Affected versionversion=13.1-FIPS <37.176
  6. Affected versionversion=14.1 <12.35

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cloud Software Group · NetScaler ADCversion=12.1-FIPS <55.302; version=12.1-NDcPP <55.302; version=13.0 <92.21; version=13.1 <51.15; version=13.1-FIPS <37.176; version=14.1 <12.35

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2Citrix Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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