Cisco ASA and FTD Cross-Site Scripting (XSS) Vulnerability

What it is

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) contain an insufficient input validation vulnerability for user-supplied input by the web services interface. Successful exploitation could allow an attacker to perform cross-site scripting (XSS) in the context of the interface or access sensitive browser-based information.

Known to be used in ransomware campaigns. Active threat actors have chained this vulnerability into ransomware operations — treat patching as a same-week priority, not a "next maintenance window" task. The fix is the same one below; the urgency is higher.

Who's affected

Affects anyone with Cisco networking or security appliances on their network — typically a firewall, switch, or remote-access VPN. That device controls traffic to and from every workstation; exploitation can mean an attacker pivots inside the network without touching any user device.

What to do

Apply updates per vendor instructions.

If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Book a free 20-minute triage call.

CISA due date

Federal deadline: May 3, 2022. Federal agencies must complete the required action by this date. For private SMBs the deadline is advisory — but treat it as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).

EPSS

EPSS score: 85.6% — higher than 100% of all scored CVEs.

EPSS estimates the probability of exploitation activity in the next 30 days. Every entry on this site is already confirmed exploited, so read it as relative urgency among the things you still have open, not as permission to wait.

Score dated 2026-08-12, from the FIRST.org Exploit Prediction Scoring System.

Other exploited Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) entries

More CISA KEV entries for Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). Same product line, same actively-exploited status.

• CVE-2024-20481: Cisco ASA and FTD Denial-of-Service Vulnerability
• CVE-2024-20353: Cisco ASA and FTD Denial of Service Vulnerability
• CVE-2024-20359: Cisco ASA and FTD Privilege Escalation Vulnerability
• CVE-2020-3259: Cisco ASA and FTD Information Disclosure Vulnerability
• CVE-2020-3452: Cisco ASA and FTD Read-Only Path Traversal Vulnerability

Browse more

• All Cisco KEV entries
• Firewalls & edge
• All SMB-relevant KEV entries

Source

This entry comes from CISA's Known Exploited Vulnerabilities catalog, public US-Government data we pull daily. The plain-language framing and the what-to-do guidance above are ours. View the original entry on cisa.gov.