CVE-2026-20039 is a denial-of-service (DoS) vulnerability affecting the VPN web server in Cisco Secure Firewall ASA and FTD Software. An unauthenticated, remote attacker can exploit this flaw by sending a high volume of specially crafted HTTP requests, leading to a device reload due to ineffective memory management. This vulnerability carries a high CVSS score of 8.6, indicating a critical impact where an attacker can cause a complete service disruption without prior authentication or user interaction. While there is no known active exploitation, public exploit code, or KEV listing, the vulnerability has garnered significant community discussion and media coverage, suggesting awareness among threat actors.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
>= 9.12.1, < 9.16.4.84CPE matchmatch criteria | cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* | ||
>= 9.17.1, < 9.18.4.57CPE matchmatch criteria | cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* | ||
>= 9.19.1, < 9.20.3.16CPE matchmatch criteria | cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* | ||
>= 9.22.1.1, < 9.22.2.4CPE matchmatch criteria | cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* | ||
>= 9.23.1, < 9.23.1.3CPE matchmatch criteria | cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.
The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.