CVEs / CVE-2025-6543
CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
- Known exploited in the CISA KEV catalog since 30 Jun 2025
- critical 9.8 CVSS 3.1 (NVD)
- EPSS 10.4% chance of exploitation in the next 30 days, higher than 95% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.
Description
Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| NetScaler ADC | from 14.1, before 47.46 | 47.46 |
| NetScaler ADC | from 13.1, before 59.19 | 59.19 |
| NetScaler ADC | from 13.1 FIPS and NDcPP, before 37.236 | 37.236 |
| NetScaler Gateway | from 14.1, before 47.46 | 47.46 |
| NetScaler Gateway | from 13.1, before 59.19 | 59.19 |
| NetScaler Gateway | from 13.1 FIPS and NDcPP, before 37.236 | 37.236 |
Exploitation
| In CISA KEV since | 30 Jun 2025 |
|---|---|
| Due date for US federal agencies | 21 Jul 2025 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. |
Severity
| CVSS 3.1 | 9.8 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HScored by NVD |
|---|---|
| Weakness | CWE-119 |
References
- CVE-2025-6543 on NVD
- CVE-2025-6543 in the CISA KEV catalog
- https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788 (cited by CISA)
- https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/ (cited by CISA)
- https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-6543 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.