CVE-2023-6549
HighExploitedPublic exploitImproper 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
Published Jan 17, 2024 · Updated Oct 21, 2025
Key Facts
Patch immediately- CVE-2023-6549 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Netscaler Application Delivery Controller (Citrix), Netscaler Gateway (Citrix).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 16, 2024. Public exploit code is available.
- EPSS estimates a 58% probability of exploitation in the next 30 days.
- Fixed versions are available, including Netscaler Application Delivery Controller 12.1-55.302, Netscaler Application Delivery Controller 13.0-92.21, Netscaler Application Delivery Controller 12.35.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
58%
Higher than 99.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-6549 brief as a PDF
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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
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Jan 17, 2024 | Feb 7, 2024 | Not reported |
| Industry KEV feed | Jan 16, 2024 | Feb 7, 2024 | Not reported |
| CIRCL KEV | Jan 17, 2024 | Feb 7, 2024 | Not reported |
| ENISA EUVD | Jan 17, 2024 | n/a | Not reported |
Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Affected Products
5 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Netscaler Application Delivery ControllerCitrix | >= 14.1 | 13.0-92.21 |
| Netscaler GatewayCitrix | See advisory | 13.0-92.21 |
Patched Releases
Netscaler Application Delivery Controller
12.1-55.302, 13.0-92.21, 12.35, 37.176, 51.15, 55.302, 92.21
Netscaler Gateway
13.0-92.21
Timeline
Added to Industry KEV feed
Jan 16, 2024
Publicly disclosed
Jan 17, 2024
Added to CISA KEV
Jan 17, 2024
Added to CIRCL KEV
Jan 17, 2024
Added to ENISA EUVD
Jan 17, 2024
Last updated
Oct 21, 2025
Weakness Type
- CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
References
- advisoryhttps://support.citrix.com/article/CTX583759/citrix-storefront-security-bulletin-for-cve20235914
- advisoryhttps://support.citrix.com/article/CTX583930/citrix-session-recording-security-bulletin-for-cve20236184
- advisoryVulnCheck exploitation report
- advisoryhttps://www.bleepingcomputer.com/news/security/citrix-warns-of-new-netscaler-zero-days-exploited-in-attacks/
- advisoryhttps://www.securityweek.com/citrix-warns-netscaler-adc-customers-of-new-zero-day-exploitation/
FAQ
Common Questions.
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: Netscaler Application Delivery Controller (Citrix) versions >= 14.1; Netscaler Gateway (Citrix). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 16, 2024.
Yes. It was added on Jan 17, 2024 with a federal remediation due date of Feb 7, 2024.
Public exploit code is available.
Fixed versions are available, including Netscaler Application Delivery Controller 12.1-55.302, Netscaler Application Delivery Controller 13.0-92.21, Netscaler Application Delivery Controller 12.35.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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