http-connection-contamination

HTTP/2 connection coalescing merges requests to subdomains sharing an IP and wildcard TLS certificate onto a single connection, allowing reverse proxies using first-request routing to misroute subsequent requests to unintended backends.

Exploit HTTP/2 connection contamination by probing for shared IPs and wildcard certificates, then reproducing the connection coalescing attack to misroute requests to sensitive admin panels or API endpoints without man-in-the-middle positioning.

Connection coalescing vulnerability occurs when multi-subdomain web applications share IP addresses and wildcard TLS certificates behind reverse proxies that use first-request connection routing to direct traffic to backends.

Yes, you can test CDN and origin setups using provided detection checklists and impact scenarios to confirm if connection coalescing conditions exist and whether the vulnerability is exploitable on the target infrastructure.

No, HTTP/2 request misrouting via connection contamination does not require man-in-the-middle positioning, as the attack exploits connection coalescing flaws directly from the client to access sensitive cross-subdomain resources.

HTTP/2 connection coalescing misrouting is limited to multi-subdomain infrastructure sharing IP addresses and wildcard TLS certificates with first-request routing proxies, and requires specific conditions to reproduce cross-subdomain request contamination successfully.