23 Oct 2026 15:48:27 UTC
Cisco Secure Firewall Threat Defense Software TLS 1.3 Denial of Service Vulnerability
cve-program · CVE-2026-20135 · Published
CVE-2026-20135
Cisco Secure Firewall Threat Defense Software TLS 1.3 Denial of Service Vulnerability
CVSS 3.1 8.6 HIGHCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-20135
PublishedA vulnerability in the TLS 1.3 implementation in Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper buffer management during the TLS 1.3 connection. An attacker could exploit this vulnerability by sending a crafted TLS 1.3 packet to an affected system through a TLS 1.3-enabled listening socket. A successful exploit could allow the attacker to cause the LINA process to crash, which would cause the device to reload. The reload can happen before or after authentication of the connection.Note: TLS 1.3 connections include both data traffic and user-management traffic.
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