CISCO: 📎 Reference: Reference: Cisco Security Advisory – cisco-sa-asaftd-dtls-dos-Kp57HkyO

CISCO Security Advisory

Published Date: Not specified

CVE: CVE-2026-20250

Advisory Summary

🗓️ 18 Sep 2026

⬛ 🔐 Title: Cisco Secure Firewall 3100/4200 DTLS DoS—Unauthenticated Remote Trigger (High)

🧨 🚨 Alarm (Security Impact: High)
Cisco reports a high-severity vulnerability affecting Cisco Secure Firewall ASA Software and Cisco Secure Firewall Threat Defense (FTD) Software on Secure Firewall 3100 and 4200 series. An attacker can send crafted DTLS traffic that triggers improper resource management, leading to a denial of service.

• Cause: Improper resource management during DTLS message handling
• Trigger: Unauthenticated attacker sends a crafted stream of DTLS messages
• Outcome: The device may reload, resulting in service disruption (DoS)

• Apply Cisco’s released software updates to remediate the issue.
• Use the provided workarounds where immediate patching isn’t feasible.

• Prioritize patching for exposed or internet-facing Secure Firewall 3100/4200 deployments, especially those with DTLS-reliant features.
• Validate whether DTLS traffic is expected from external sources; if not, tighten network/ACL posture as an interim control until updates are applied.
• Schedule change windows because DoS conditions may impact availability during an active exploit attempt.

• CVE-2026-20250

Reference: Vendor Advisory