CVE-2025-20333CiscoFirewall and VPNSeptember 25, 2025

Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability

Critical 9.9Actively exploited

Description

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.

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.

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Details

Vendor
Cisco
Product
Cisco ASA e FTD
CVE
CVE-2025-20333
Affected versions
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.8: 50 versions, from 9.8.1 to 9.8.4.48
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.12: 42 versions, from 9.12.1 to 9.12.4.67
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.14: 29 versions, from 9.14.1 to 9.14.4.24
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.16: 34 versions, from 9.16.1 to 9.16.4.84
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.17: 11 versions, from 9.17.1 to 9.17.1.39
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.18: 20 versions, from 9.18.1 to 9.18.4.40
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.19: 10 versions, from 9.19.1 to 9.19.1.31
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.20: 8 versions, from 9.20.1 to 9.20.3.4
Cisco Secure Firewall Adaptive Security Appliance (ASA) Soft 9.22: 9.22.1.1; 9.22.1.2
Cisco Secure Firewall Threat Defense (FTD) Software 6.2: 19 versions, from 6.2.3 to 6.2.3.18
Cisco Secure Firewall Threat Defense (FTD) Software 6.6: 11 versions, from 6.6.0 to 6.6.7.2
Cisco Secure Firewall Threat Defense (FTD) Software 6.4: 19 versions, from 6.4.0 to 6.4.0.18
Cisco Secure Firewall Threat Defense (FTD) Software 7.0: 15 versions, from 7.0.0 to 7.0.8
Cisco Secure Firewall Threat Defense (FTD) Software 7.1: 4 versions, from 7.1.0 to 7.1.0.3
Cisco Secure Firewall Threat Defense (FTD) Software 7.2: 14 versions, from 7.2.0 to 7.2.8.1
Cisco Secure Firewall Threat Defense (FTD) Software 7.3: 4 versions, from 7.3.0 to 7.3.1.2
Cisco Secure Firewall Threat Defense (FTD) Software 7.4: 7 versions, from 7.4.0 to 7.4.2.3
Cisco Secure Firewall Threat Defense (FTD) Software 7.6: 7.6.0 (from the advisory and NVD; check the exact builds in the official advisory)
CVSS score
9.9
Actively exploited
Yes, listed in the CISA Known Exploited Vulnerabilities catalog
CISA due date
September 26, 2025 (deadline for US federal agencies: a good benchmark for you too)
Source
CISA KEV – original advisory
Published
September 25, 2025

The description and the recommended action are quoted from the public advisory; severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.

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