CSIRTS // UNIFIED SECURITY ADVISORY FEEDSYS ● ONLINE · POWERED BY INTELFUSIONS.COM

← Back to feed

CVE-2025-20333: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability

criticalknown exploitedpublic exploitCVE-2025-20333
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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.

CSIRTS triage

vendor: Ciscoproduct: Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)Remote code execution
What
The vulnerability allows for remote code execution due to a buffer overflow.
Who is affected
Users of Cisco Secure Firewall ASA and FTD Software VPN Web Server.
Urgency
Remediation is critical as the vulnerability is actively exploited and poses a severe risk.
Action
Apply the latest security updates from Cisco.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)

Get an email when a new Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) advisory drops — max one per day, one-click unsubscribe.

Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2025-09-25
Exploitation
Observed in the wild (CISA KEV)

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

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2025-20333coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Cisco Secure Firewall

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

More from CISA Known Exploited Vulnerabilities