CVE-2026-55996 Unauthenticated Denial-of-Service via TLS SAN Stuffing in Rancher and cattle-cluster-agent

A denial-of-service vulnerability was identified in multiple TLS listeners in Rancher. Both the cattle-cluster-agent component running in downstream clusters and the Rancher server itself use the dynamiclistener library to serve TLS traffic. Without an effective CN filter configured,...

GHSA-M4HF-6VGR-75R2 K3s apiserver port is vulnerable to unauthenticated remote denial-of-service (DoS) attack via TLS SAN stuffing attack

Impact An issue was found in K3s where an attacker with network access to K3s servers' apiserver/supervisor port TCP 6443 can force the TLS server to add entries to the certificate's Subject Alternative Name SAN list, through a stuffing attack, until the certificate grows so large that it exceeds...

K3s apiserver port is vulnerable to unauthenticated remote denial-of-service (DoS) attack via TLS SAN stuffing attack

Impact An issue was found in K3s where an attacker with network access to K3s servers' apiserver/supervisor port TCP 6443 can force the TLS server to add entries to the certificate's Subject Alternative Name SAN list, through a stuffing attack, until the certificate grows so large that it exceeds...