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CVE · Exploited · On CISA KEV

CVE-2025-20333

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

9.9
CVSS 3.1
2
stories
SEP 25
added to KEV
Severity
9.9 Critical · vendor score
Vendor
Cisco
Product
Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense
Published
Sep 25, 2025
Added to KEV
Sep 25, 2025
KEV deadline
Sep 26, 2025
Ransomware use
Unknown
Weakness
CWE-120
Part of Cisco ASA Zero-Day Attacks →

What it is

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's Known Exploited Vulnerabilities catalog

Decipher coverage · 2 stories

Newest first ↑
  1. IntrusionsCisco Warns of Attacks on Two ASA FlawsCisco’s Talos threat intelligence team said this campaign is the work of an actor it tracks as UAT4356, an APT team that has previously targeted ASA devices.DENNIS FISHER · 3 MIN
  2. PolicyFirestarter Malware Sparks Updated CISA Emergency DirectiveCISA is warning of a persistent backdoor called Firestarter that’s being used in attacks against Cisco Firepower and Secure Firewall products.LINDSEY O'DONNELL-WELCH · 4 MIN

Official references

5 sources

Registries

RegistryNVDScore, weakness and every referenceRegistryCVE.orgThe official CVE recordRegistryCISA KEVKnown exploited, with the federal deadline

Advisories, fixes & analysis

Vendor advisorysec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUBVendor advisorysec.cloudapps.cisco.com/security/center/resources/asa_ftd_continued_attacks