Exploited CVEs / Cisco / CVE-2025-20333
CVE-2025-20333
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2025-09-26 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Cisco Security Advisories (PSIRT), linked below.
Actively exploited Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense vulnerability, Critical severity, CVSS 9.9. Added to the CISA KEV catalog 2025-09-25.
Risk summary
Updated July 27, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2025-20333
The code execution half of the Cisco ASA and FTD chain: a buffer overflow in the VPN web server rated CVSS 9.9 that pairs with the CVE-2025-20362 authorization bypass for full unauthenticated device takeover. These are perimeter security appliances, so successful exploitation is a network-wide event; KEV-listed September 2025.
Do this: Patch every ASA and FTD device now and treat any that were exposed unpatched as candidates for forensic review, not just remediation.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2025-20333
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2025-20333
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: 2025-09-26 (past due).
The KEV due date refers to the deadline by which FCEB agencies are expected to review and begin implementing the guidance outlined in Emergency Directive (ED) 25-03 (URL listed below in Notes). Agencies must follow the mitigation steps provided by CISA (URL listed below in Notes) and vendor’s instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.
Official fix for CVE-2025-20333
The authoritative fix and affected-version list are published by the vendor. Find the Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense advisory on Cisco Security Advisories (PSIRT).
Common questions about CVE-2025-20333
Is CVE-2025-20333 actively exploited?
Yes. CVE-2025-20333 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2025-09-25, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 40%.
What is the CISA deadline and required action for CVE-2025-20333?
CISA set the federal (BOD 22-01) remediation due date at 2025-09-26, which has passed; treat any unremediated system as overdue. The verbatim required action: The KEV due date refers to the deadline by which FCEB agencies are expected to review and begin implementing the guidance outlined in Emergency Directive (ED) 25-03 (URL listed below in Notes). Agencies must follow the mitigation steps provided by CISA (URL listed below in Notes) and vendor’s instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.
What fixes CVE-2025-20333?
The authoritative fix is in the vendor advisory: see Cisco Security Advisories (PSIRT) for the patched Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense 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-2025-20333?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2025-20333'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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