Threats / Cisco / CVE-2020-3580
CVE-2020-3580
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Cisco Adaptive Security Appliance (ASA) and Firepower Threat vulnerability
Cisco ASA and FTD web interface contains insufficient input validation allowing cross-site scripting (XSS) attacks that could expose sensitive information or compromise administrator sessions.
Verdict
Today item, not a backlog item.
A reflected or stored XSS vulnerability in the web management interface of Cisco ASA/FTD enables attackers to inject malicious scripts. With high EPSS and active exploitation, this poses significant risk to firewall administrators and network security posture.
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
375 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.85439 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Cisco, Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD). Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-79 Cross-site Scripting (XSS) — weakness family: Web / client.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious URL or inject script payload into the ASA/FTD web interface input fields.
Business
Attackers gain ability to execute arbitrary JavaScript in administrator browsers, risking credential theft and unauthorized firewall reconfiguration.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I execute the XSS payload to steal session cookies or authentication tokens from logged-in administrators.
Business
Compromise of admin credentials enables lateral movement into protected networks and potential deployment of ransomware or persistent backdoors.
3
Lateral reach — past segmentation narrative 3
Attacker
I use the compromised firewall access to modify security policies, disable logging, or establish command-and-control channels.
Business
Loss of perimeter security control, undetected data exfiltration, and inability to respond to or investigate security incidents.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05