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

<p>Cloudflare IPsec now supports the <a href="https://datatracker.ietf.org/doc/draft-ietf-ipsecme-ikev2-downgrade-prevention/" target="_blank" rel="noopener"><code>IKE_SA_INIT_FULL_TRANSCRIPT_AUTH</code><span class="external-link"> ↗︎</span></a> IKEv2 extension to protect against downgrade attacks on IPsec tunnels.</p> <p>IKEv2's original authentication design has each endpoint sign only its own outbound messages, not the full handshake transcript. A quantum-capable <a href="https://www.cloudflare.com/learning/security/threats/on-path-attack/" target="_blank" rel="noopener">on-path attacker<span class="external-link"> ↗︎</span></a> can exploit this to bypass post-quantum key exchange by downgrading the connection to classical cryptography. The <code>IKE_SA_INIT_FULL_TRANSCRIPT_AUTH</code> 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.</p> <p>Key details:</p> <ul> <li>Available in beta for Cloudflare WAN and Magic Transit IPsec tunnels.</li> <li>Cloudflare sends the <code>IKE_SA_INIT_FULL_TRANSCRIPT_AUTH</code> notification unconditionally as a responder when the feature flag is enabled.</li> <li>Both the initiator (your device) and responder (Cloudflare) must support the extension for downgrade protection to be effective.</li> <li>This feature is currently gated by a per-account feature flag. Contact your account team to turn it on.</li> </ul> <p>Refer to <a href="https://developers.cloudflare.com/cloudflare-wan/reference/gre-ipsec-tunnels/#improved-downgrade-protection-beta">Downgrade protection</a> for more details.</p>