Exploited CVEs / Citrix / CVE-2025-6543
CVE-2025-6543
Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2025-07-21 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Citrix Security Bulletins, linked below.
Actively exploited Citrix NetScaler ADC and Gateway vulnerability, Critical severity, CVSS 9.8. Added to the CISA KEV catalog 2025-06-30.
Risk summary
Updated July 26, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2025-6543
A buffer overflow in Citrix NetScaler ADC and Gateway causing unintended control flow and denial of service when the appliance is configured as a Gateway or AAA virtual server, CVSS 9.8. It was exploited in the wild by the end of June 2025, part of a summer in which NetScaler appliances were hit by multiple memory safety flaws in quick succession.
Do this: Bring all NetScaler firmware current and confirm your build covers this CVE along with the related summer 2025 fixes.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2025-6543
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2025-6543
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal (BOD 22-01) remediation due date: 2025-07-21 (past due).
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Official fix for CVE-2025-6543
The authoritative fix and affected-version list are published by the vendor. Find the NetScaler ADC and Gateway advisory on Citrix Security Bulletins.
Common questions about CVE-2025-6543
Is CVE-2025-6543 actively exploited?
Yes. CVE-2025-6543 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2025-06-30, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 9.8%.
What is the CISA deadline and required action for CVE-2025-6543?
CISA set the federal (BOD 22-01) remediation due date at 2025-07-21, which has passed; treat any unremediated system as overdue. The verbatim 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.
What fixes CVE-2025-6543?
The authoritative fix is in the vendor advisory: see Citrix Security Bulletins for the patched NetScaler ADC and Gateway versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2025-6543?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2025-6543's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
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Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.
