Ssl Verify Fun
Monthly
Hostname verification in the Erlang library ssl_verify_fun (versions 1.0.1 through 1.1.7) mishandles partial-label wildcard certificate identifiers, letting a certificate such as f*.example.net be accepted for f.evil.example.net. A man-in-the-middle holding such a certificate from a CA the victim trusts could impersonate the peer, but only where ssl_verify_fun is the sole hostname check - clients with server_name_indication disabled, TLS servers using it to check client certificates, direct callers of verify_cert_hostname/2, or Erlang/OTP older than 20.0, since OTP 20.0+ with SNI set rejects the mismatch in ssl first. Fixed in 1.1.8; no public exploit identified at time of analysis, though a detailed proof-of-concept procedure is published in the advisory.
Hostname verification in the Erlang library ssl_verify_fun (versions 1.0.1 through 1.1.7) mishandles partial-label wildcard certificate identifiers, letting a certificate such as f*.example.net be accepted for f.evil.example.net. A man-in-the-middle holding such a certificate from a CA the victim trusts could impersonate the peer, but only where ssl_verify_fun is the sole hostname check - clients with server_name_indication disabled, TLS servers using it to check client certificates, direct callers of verify_cert_hostname/2, or Erlang/OTP older than 20.0, since OTP 20.0+ with SNI set rejects the mismatch in ssl first. Fixed in 1.1.8; no public exploit identified at time of analysis, though a detailed proof-of-concept procedure is published in the advisory.