---
title: "CVE-2023-6549: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability"
url: https://erroneo.us/security/cve/CVE-2023-6549/
description: "CVE-2023-6549 (Citrix NetScaler ADC and NetScaler Gateway): Exploited in the wild (CISA KEV). Improper Restriction of Operations within the Bounds of a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-01-17
date_modified: 2025-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2023-6549"
kev: true
cvss: 8.2
epss: 0.57633
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2023-6549: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Citrix NetScaler ADC and NetScaler Gateway. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2024-01-17, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2024-02-07 ; treat that as the outer limit, not the target.
- EPSS 57.6% , percentile 99: FIRST’s model estimates a 57.6% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it is

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 products (CVE record)

- Cloud Software Group NetScaler ADC: 14.1 < 12.35, 13.1 < 51.15, 13.0 < 92.21, 13.1-FIPS < 37.176, 12.1-FIPS < 55.302, 12.1-NDcPP < 55.302

## Severity

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

## Exploitation

- CISA KEV: added 2024-01-17; federal due date 2024-02-07. Known ransomware use: Unknown.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 57.63% probability of exploitation activity in the next 30 days; percentile 99.

## Sources

- [Listed in CISA KEV notes (support.citrix.com)](https://support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549)
- [CVE.org record CVE-2023-6549](https://www.cve.org/CVERecord?id=CVE-2023-6549)
- [NVD entry CVE-2023-6549](https://nvd.nist.gov/vuln/detail/CVE-2023-6549)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-6549)

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Source page: https://erroneo.us/security/cve/CVE-2023-6549/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt