CVE Record
[ HIGH ]CVE-2024-20353
Cisco ASA and FTD Denial of Service Vulnerability
Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an infinite loop vulnerability that can lead to remote denial of service condition.
- Vendor
- Cisco
- Product
- Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)
- CVSS
- 8.6
- EPSS (exploit probability)
- 70.7%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2024-20353 being exploited?
Yes. CISA added CVE-2024-20353 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 70.7% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-19. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
US federal civilian agencies must remediate by (7 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-20349 Cisco ASA and FTD VPN Heap Inspection Denial-of-Service Flawwrite-up | [ HIGH ] | 8.6 | 1.0% | |
| CVE-2025-20362 Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Missing Authorization Vulnerability | [ MEDIUM ] | 6.5 | 87.1% | |
| CVE-2025-20333 Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability | [ CRITICAL ] | 9.9 | 71.2% | |
| CVE-2024-20481 Cisco ASA and FTD Denial-of-Service Vulnerability | [ MEDIUM ] | 5.8 | 15.9% | |
| CVE-2024-20359 Cisco ASA and FTD Privilege Escalation Vulnerability | [ MEDIUM ] | 6.0 | 19.4% | |
| CVE-2020-3259 Cisco ASA and FTD Information Disclosure Vulnerabilityransomware use | [ HIGH ] | 7.5 | 71.8% | |
| CVE-2023-20269 Cisco Adaptive Security Appliance and Firepower Threat Defense Unauthorized Access Vulnerabilityransomware use | [ MEDIUM ] | 5.0 | 25.5% | |
| CVE-2020-3580 Cisco ASA and FTD Cross-Site Scripting (XSS) Vulnerabilityransomware use | [ MEDIUM ] | 6.1 | 85.6% |