9.8

CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

CVSS: 9.8v3.1CriticalKEVAnalyzed
Published 25-06-2025Last modified 26-02-2026
Open JSON

Vulnerability summary

CVE-2025-6543 is a critical (CVSS 9.8) vulnerability in Citrix NetScaler ADC and Gateway. It is known to be exploited: CISA and ENISA list it, first on 30-06-2025. EPSS estimates a 10.56% chance of exploitation in the next 30 days, higher than 95.7% of scored vulnerabilities.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (NVD)
EPSS score
10.56%
0%100%
Medium · +0.42 pp in 30 days
KEVListedCISA · ENISA
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 25-06-2025
    PublishedVulnerability first disclosed.
  2. 30-06-2025
    Added to CISA KEVCitrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
  3. 18-07-2025
    Added to ENISA KEVAdded to the ENISA known exploited vulnerabilities catalog.
  4. 21-07-2025
    CISA remediation dueApply mitigations per vendor instructions.
  5. 26-02-2026
    Last modifiedVulnerability information updated.

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

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

10.56%

Chance of exploitation in the next 30 days

Percentile

96%

Versus all other CVEs

30-day change

+0.42 pp

From 10.14% on 19-09-2026

19-09-202619-10-2026
EPSS score
10.56%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
30-06-2025
Federal due date
21-07-2025
ENISA CNWListed
Added
18-07-2025

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. support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788 www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/ nvd.nist.gov/vuln/detail/CVE-2025-6543

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Citrix2 products
Netscaler2 products
  • adc≥ 14.1, < 47.46 | ≥ 13.1, < 59.19 | ≥ 13.1 FIPS and NDcPP, < 37.236
  • gateway≥ 14.1, < 47.46 | ≥ 13.1, < 59.19 | ≥ 13.1 FIPS and NDcPP, < 37.236

2 vendors · 4 products

References

2 links