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 402 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)
- 70.6% probability of exploitation in the next 30 days, higher than 99.3% 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 2026-02-26
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. Weaponised exploit code for CVE-2025-20333 is publicly available. 4 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 53 in the Threadlinqs vulnerability feed.
- curtishoughton/Cisco-ASA-CVE-2025-20333-Scanner (github)
- cobbbex/Cisco-ASA-vulnerability-research (github)
- cobbbex/cve-2025-20333 (github)
- trickest/cve (trickest)
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
4 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.
- Rapid7 Q3 2026 Threat Landscape: High-Severity Flaws Exploited in 3 Days as The Gentlemen and Qilin Ransomware Dominate — HIGH · 2026-10-21
- 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
- Coordinated Scanning Campaign Against Fortinet SSL VPN and Palo Alto GlobalProtect Infrastructure Detected via GreyNoise Vendor CVE / Tag Spike Signals — MEDIUM · 2026-01-25
Sources
Enriched from CVE.org, FIRST EPSS, CISA KEV, public proof-of-concept repositories. Last verified by Threadlinqs on .