Cloudflare One, Cloudflare WAN - IPsec downgrade protection (beta)

Cloudflare IPsec now supports the IKE_SA_INIT_FULL_TRANSCRIPT_AUTH IKEv2 extension to protect against downgrade attacks on IPsec tunnels. IKEv2's original authentication design has each endpoint sign only its own outbound messages, not the full handshake transcript. A quantum-capable on-path attacker can exploit this to bypass post-quantum key exchange by downgrading the connection to classical cryptography. The IKE_SA_INIT_FULL_TRANSCRIPT_AUTH extension addresses this by having both peers sign the entire handshake transcript during the authentication exchange, preventing an attacker from manipulating the negotiation without detection. Key details: Available in beta for Cloudflare WAN and Magic Transit IPsec tunnels. Cloudflare sends the IKE_SA_INIT_FULL_TRANSCRIPT_AUTH notification unconditionally as a responder when the feature flag is enabled. Both the initiator (your device) and responder (Cloudflare) must support the extension for downgrade protection to be effective. This feature is currently gated by a per-account feature flag. Contact your account team to turn it on. Refer to Downgrade protection for more details.