Home / Vulnerabilities / CVE-2025-20333
CRITICAL SEVERITY
CVE-2025-20333 Cisco · Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense

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

Technical Severity

CVSS v3.1 Metrics

CRITICAL
9.9 / 10
Minimal Risk Critical
Vector Specification
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Exploitation Likelihood

EPSS Prediction

18.66 %
Predictive Probability
Percentile Rank
95.1 th

Documented as more likely to be exploited than 95.1% of known CVEs.

Detection Date

Sep 25, 2025

Remediation Due

Sep 26, 2025

CISA Catalog Active

Threat Analysis

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.

Remediation Directive

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.

External Intelligence

CISA

CISA Advisory

https://www.cisa.gov/news-events/directives/ed-25-03-identify-and-mitigate-potential-compromise-cisco-devices
CISA

CISA Advisory

https://www.cisa.gov/news-events/directives/supplemental-direction-ed-25-03-core-dump-and-hunt-instructions
CISA

CISA Advisory

https://www.cisa.gov/eviction-strategies-tool/create-from-template

https://sec.cloudapps.cisco.com/security/center/resources/asa_ftd_continued_attacks

https://sec.cloudapps.cisco.com/security/center/resources/asa_ftd_continued_attacks

https://sec.cloudapps.cisco.com/security/center/private/resources/asa_ftd_continued_attacks#Details

https://sec.cloudapps.cisco.com/security/center/private/resources/asa_ftd_continued_attacks#Details

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB
NVD

National Vulnerability Database

https://nvd.nist.gov/vuln/detail/CVE-2025-20333