CVE-2025-20333 — Cisco Adaptive Security Appliance Software
CISA KEVAs of 2025-10-28, CVE-2025-20333 is a CRITICAL-severity vulnerability in Cisco Adaptive Security Appliance Software, CVSS v3.1 9.9, EPSS 41.4% (97.4th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-09-25), with a US federal remediation deadline of 2025-09-26. Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2025-20333, most recently “AhnLab ASEC April 2026 APT Group Trend Report: State-Sponsored Espionage Campaigns (CVE-2026-32202, CVE-2025-20333/20362, CVE-2021-26855)”.
Last updated: 2025-10-28
What is CVE-2025-20333?
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.
The record classifies CVE-2025-20333 under weakness class CWE-120. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 353 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.9 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 41.4% probability of exploitation in the next 30 days, higher than 97.4% of all scored CVEs
- CISA KEV
- Listed since 2025-09-25, federal remediation deadline 2025-09-26
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2025-09-25, last modified 2025-10-28
Is CVE-2025-20333 being exploited?
CISA added CVE-2025-20333 to the Known Exploited Vulnerabilities catalog on 2025-09-25, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2025-09-26 under BOD 22-01. It currently carries a trending score of 39 in the Threadlinqs vulnerability feed.
Affected products and versions
- Cisco: Adaptive Security Appliance Software, Firepower Threat Defense, Firepower Threat Defense 7.6.0
How to fix CVE-2025-20333
The record marks a vendor fix as available for CVE-2025-20333. Vendor advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-webvpn-z5xP8EUB. Because CVE-2025-20333 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2025-09-26. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2025-20333
2 tracked threats in the Threadlinqs corpus reference CVE-2025-20333, either in the campaign’s CVE list or as an indicator on the campaign record.
- AhnLab ASEC April 2026 APT Group Trend Report: State-Sponsored Espionage Campaigns (CVE-2026-32202, CVE-2025-20333/20362, CVE-2021-26855) — HIGH · 2026-06-10
- Firestarter Malware Persists on Cisco ASA/Firepower Through Firmware Updates (CVE-2025-20333, CVE-2025-20362) — UAT-4356/ArcaneDoor — CRITICAL · 2026-04-24
Sources
Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.
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