CVE-2026-20135

Name of the Vulnerable Software and Affected Versions Cisco Secure Firewall Threat Defense (FTD) Software (affected versions not specified)

Description An issue in the TLS 1.3 implementation allows an unauthenticated remote attacker to cause a device to reload unexpectedly, leading to a denial of service. This occurs due to improper buffer management during a TLS 1.3 connection. An attacker can trigger the crash of the LINA process by sending a crafted TLS 1.3 packet to a listening socket enabled for TLS 1.3. This impact applies to both data traffic and user-management traffic, and the reload can occur regardless of whether the connection has been authenticated.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.