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CVE-2025-20333

CRITICAL KEV CISA Exploitation: ACTIVE
9.9
CVSS 3.1
Description
A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP(S) requests. An attacker with valid VPN user credentials could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as root, possibly resulting in the complete compromise of the affected device.

Metadata

CVE ID
CVE-2025-20333
State
PUBLISHED
Assigner
cisco
Reserved
2024-10-10 19:15 UTC
Published
2025-09-25 16:12 UTC
Last updated
2026-02-26 17:47 UTC
Primary CWE
CWE-120
Buffer Copy without Checking Size of Input ('Classic Buffer …
Vendor / Product
Cisco / Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Sources
cve.org  ·  NVD

Severity & Metrics

9.9 CRITICAL CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
SSVC — CISA Coordinator
Exploitation
ACTIVE
Automatable
no
Tech. Impact
total
CISA Known Exploited Vulnerability
Vulnerability name
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow Vulnerability
Vendor
Cisco
Product
Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense
Added to KEV
2025-09-25
Due date
2025-09-26
Ransomware
Not known
Required action
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.
CISA description
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.
Affected products (2)
VendorProductPlatformVersions
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software — 9.8.1, 9.8.1.5, 9.8.1.7, 9.8.2 …
Cisco Cisco Secure Firewall Threat Defense (FTD) Software — 6.2.3, 6.2.3.1, 6.2.3.2, 6.2.3.3 …
Weakness (CWE)
CWESourceDescription
CWE-120 cna Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CVSS scores (1)
ScoreSeverityVersionSourceVector
9.9 CRITICAL 3.1 cna CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
References (1)
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