Exploited CVEs / Cisco / CVE-2024-20353
CVE-2024-20353
Cisco ASA and FTD Denial of Service Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2024-05-01 (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 Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) vulnerability, High severity, CVSS 8.6. Added to the CISA KEV catalog 2024-04-24.
Risk summary
Updated July 27, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2024-20353
An infinite loop in Cisco ASA and FTD lets a remote attacker knock the firewall into a reload at will, and in observed attacks the forced reboots were used as part of a larger appliance compromise rather than as simple disruption. With CVSS 8.6, a 63 percent EPSS, and an April 2024 KEV entry, unexplained ASA reboots deserve to be treated as an indicator, not an annoyance. Denial of service against your perimeter firewall also means VPN and segmentation outages for everyone behind it.
Do this: Patch ASA and FTD devices and pull reboot histories from the last months, investigating any restart you cannot attribute to your own changes.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2024-20353
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2024-20353
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: 2024-05-01 (past due).
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Official fix for CVE-2024-20353
The authoritative fix and affected-version list are published by the vendor. Find the Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) advisory on Cisco Security Advisories (PSIRT).
Common questions about CVE-2024-20353
Is CVE-2024-20353 actively exploited?
Yes. CVE-2024-20353 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2024-04-24, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 71%.
What is the CISA deadline and required action for CVE-2024-20353?
CISA set the federal (BOD 22-01) remediation due date at 2024-05-01, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
What fixes CVE-2024-20353?
The authoritative fix is in the vendor advisory: see Cisco Security Advisories (PSIRT) for the patched Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) 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-2024-20353?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2024-20353'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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