CVE-2025-20333

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

9.9 CRITICALActively exploited (CISA KEV)EPSS 70.7%

Published25 Sept 2025
Added to CISA KEV25 Sept 2025
Remediation due26 Sept 2025

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.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredLow

User interactionNone

ScopeChanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

Cisco Secure Firewall Threat Defense≥ 7.0.0 < 7.0.8.1 · ≥ 7.1.0 < 7.2.9 · ≥ 7.3.0 < 7.4.2.4 · 7.6.0

Cisco Adaptive Security Appliance Software≥ 9.12 < 9.12.4.72 · ≥ 9.14 < 9.14.4.28 · ≥ 9.16 < 9.16.4.85 · ≥ 9.17.0 < 9.17.1.45

Remediation

Fixed in

Cisco Secure Firewall Threat Defense≥ 7.0.8.1

Cisco Adaptive Security Appliance Software≥ 9.12.4.72

Patch & vendor advisories

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUBVendor Advisory
https://sec.cloudapps.cisco.com/security/center/resources/asa_ftd_continued_attacksVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-20333US Government Resource

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2025-20333 being actively exploited?

Yes. CVE-2025-20333 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 25 Sept 2025.

How severe is CVE-2025-20333?

CVE-2025-20333 has a CVSS 3.1 base score of 9.9, rated critical. EPSS estimates a 70.7% probability of exploitation.

Which products are affected by CVE-2025-20333?

Affected products include Cisco Secure Firewall Threat Defense, Cisco Adaptive Security Appliance Software.

How do I fix CVE-2025-20333?

Upgrade affected software to a fixed version, for example Cisco Secure Firewall Threat Defense 7.0.8.1, Cisco Adaptive Security Appliance Software 9.12.4.72 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-20333 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.