CVE-2023-6549

Exp

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

Published: 2024-01-17 Last update: 2026-02-26 Assigner: [email protected] Source: [email protected]

NVD Status：Analyzed，CVE State: published

View at NVD, CVE.org, EUVD

Threat Intelligence & Risk Assessment for CVE-2023-6549

KEV EPSS CVSS CWE Affected

Conclusion & alert: CVE-2023-6549 is rated Critical Active Threat (94.6/100): CVSS High severity, with high exploitation likelihood (EPSS 82.32%, 99th percentile). Core evidence: CISA KEV confirms active exploitation (added 2024-01-17) affecting Citrix / NetScaler ADC and NetScaler Gateway. a weakness (CWE-119) Unauthenticated remote administrative access may be possible. EPSS rose +2.08% over the last day, indicating growing attacker interest. Mandatory action: The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2023-6549

Name: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability · CISA KEV detail

Exploit added: 2024-01-17

Action due: 2024-02-07

Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Exploit prediction scoring system (EPSS) score for CVE-2023-6549

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-11	80.24%	82.32%	+2.08%
2	2026-05-27	79.86%	80.24%	+0.38%
3	2026-05-14	—	79.86%	—

Full EPSS history (55 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-6549

CVSS metrics for this CVE.

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.2	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	4.2	[email protected]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]

Weakness enumeration for CVE-2023-6549

CWE-119 MITRE ↗

Affected software / configurations for CVE-2023-6549

Vendor	Product	Version	Raw CPE
citrix	netscaler_application_delivery_controller	>= 12.1, < 12.1-55.302	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::fips:::*
citrix	netscaler_application_delivery_controller	>= 12.1, < 12.1-55.302	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::ndcpp:::*
citrix	netscaler_application_delivery_controller	>= 13.0, < 13.0-92.21	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::-:::*
citrix	netscaler_application_delivery_controller	>= 13.1, < 13.1-37.176	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::fips:::*
citrix	netscaler_application_delivery_controller	>= 13.1, < 13.1-51.15	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::-:::*
citrix	netscaler_application_delivery_controller	>= 14.1, < 14.1-12.35	cpe:2.3:a:citrix:netscaler_application_delivery_controller:::::-:::*
citrix	netscaler_gateway	>= 13.0, < 13.0-92.21	cpe:2.3:a:citrix:netscaler_gateway::::::::
citrix	netscaler_gateway	>= 13.1, < 13.1-51.15	cpe:2.3:a:citrix:netscaler_gateway::::::::
citrix	netscaler_gateway	>= 14.1, < 14.1-12.35	cpe:2.3:a:citrix:netscaler_gateway::::::::

References for CVE-2023-6549

URL	Tags
https://support.citrix.com/article/CTX584986/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20236548-and-cve20236549	Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-6549	US Government Resource

cvelogic Threat Intelligence