CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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
Description quoted from the CVE record (assigned by Citrix, published 2025-06-25).
Weakness: CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
How it can be exploited
Exploitable over the network with high attack complexity only when specific conditions are present needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L
CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.
- On CISA KEV since
- 2025-06-30
- US federal deadline
- 2025-07-21
- Ransomware use
- Not known
Public exploit evidence (Exploit Observer)
Also known as: BDU:2025-09120, CNNVD-202506-3148, EUVD-2025-19085, GHSA-9gqr-6728-fpv3
VEDAS cluster: VEDAS:GARNETGOLEM
Exploit Observer links 4 pieces of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (4)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/abrewer251/cve-2025-6543_citrixnetscaler_poc
- Code repository: https://github.com/grupooruss/citrix-cve-2025-6543
- Code repository: https://github.com/lex1010/cve-2025-6543
- Code repository: https://github.com/seabed-atavism/cve-2025-6543
Vulnerability databases and vendor advisories (7)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2025-19085
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-9gqr-6728-fpv3
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-6543
- Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-6543
- Vulnerability database or vendor advisory: https://www.cnnvd.org.cn/home/globalSearch?keyword=CNNVD-202506-3148
- Vulnerability database or vendor advisory: https://www.esentire.com/security-advisories/actively-exploited-citrix-vulnerability-cve-2025-6543
- Vulnerability database or vendor advisory: https://www.tenable.com/cve/CVE-2025-6543
News (1)
62 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.104
likely to be attacked soon - VEDAS
- 0.972
strong exploit evidence - On CISA KEV
- Yes, since 2025-06-30
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| NetScaler ADC | from 14.1 before 47.46 from 13.1 before 59.19 from 13.1 FIPS and NDcPP before 37.236 | Not stated |
| NetScaler Gateway | from 14.1 before 47.46 from 13.1 before 59.19 from 13.1 FIPS and NDcPP before 37.236 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
Exploit Observer also maps it to: citrix netscaler_application_delivery_controller, citrix netscaler_gateway, citrix_systems_inc. netscaler_application_delivery_controller, citrix_systems_inc. netscaler_gateway.
How to fix it
Fixed versions stated in the CVE record: 47.46, 59.19, 37.236.
CISA 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.
Vendor guidance:
- https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788
- https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/
- https://nvd.nist.gov/vuln/detail/CVE-2025-6543
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
References
Government sources
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-6543 (government-resource)
Other references
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.