A flaw was found in submariner. In cert-auth mode, the connection configuration is built using free-form strings from the Custom Resource Definition (CRD) without proper validation. A malicious cluster can exploit this by publishing a CableName that includes newlines and ipsec.conf directives. This allows an attacker to inject arbitrary configuration parameters or execute commands through leftupdown hooks, leading to remote code execution as root on the gateway node.
If Submariner certificate-based IPsec authentication mode is enabled (IPSecCertAuthMode: true in the SubmarinerConfig), administrators can mitigate this flaw by switching to the default pre-shared key (PSK) authentication mode. Set IPSecCertAuthMode: false (or remove the field to use its default value) in the SubmarinerConfig CR and redeploy the Submariner gateway pods. PSK mode provides equivalent inter-cluster IPsec tunnel encryption and is not affected by this vulnerability. Note that disabling cert-auth mode means Submariner will no longer integrate with OVN IPsec's certificate infrastructure and will manage its own PSK-based authentication independently.