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VulnerabilityKnown exploitedExploit likelihood 72%
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability
CVE-2025-20333 · CISA KEV · September 25, 2025
Summary
Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Software VPN Web Server contain a buffer overflow vulnerability that allows for remote code execution. This vulnerability could be chained with CVE-2025-20362.
From CISA, quoted as published. Check the source before acting.
What to do
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.
CISA required action, quoted.
Affected products
| Vendor | Product |
|---|---|
| Cisco | Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense |
Why it's on these mode pages
- Maritime: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
- Pipeline: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
- Freight rail: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
- Passenger rail and transit: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
- Highway and motor carrier: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
- Postal and parcel: Vendor table: Cisco (network and remote-access gear used in every mode, all modes) (matched by rule)
Change history
- November 9, 2026: First collected by Watch
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