{"id":"GHSA-f5v5-ccqc-6w36","aliases":["RUSTSEC-2023-0027"],"url":"https://o3.security/vulnerability/GHSA-f5v5-ccqc-6w36","summary":"async-nats vulnerable to TLS certificate common name validation bypass","details":"The NATS official Rust clients are vulnerable to MitM when using TLS.\n\nThe common name of the server's TLS certificate is validated against the `host`name provided by the server's plaintext `INFO` message during the initial connection setup phase. A MitM proxy can tamper with the `host` field's value by substituting it with the common name of a valid certificate it controls, fooling the client into accepting it.\n\n## Reproduction steps\n\n1. The NATS Rust client tries to establish a new connection\n2. The connection is intercepted by a MitM proxy\n3. The proxy makes a separate connection to the NATS server\n4. The NATS server replies with an `INFO` message\n5. The proxy reads the `INFO`, alters the `host` JSON field and passes the tampered `INFO` back to the client\n6. The proxy upgrades the client connection to TLS, presenting a certificate issued by a certificate authority present in the client's keychain. In the previous step the `host` was set to the common name of said certificate\n7. `rustls` accepts the certificate, having verified that the common name matches the attacker-controlled value it was given\n8. The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate\n","published":"2023-03-24T21:59:53Z","modified":"2023-11-08T04:18:50.210490Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"async-nats","fixedVersion":"0.29.0"}],"fix":{"url":"https://github.com/nats-io/nats.rs/commit/817a7b942c462fa9d9938dcb62124173634132fb#diff-767d442397fcaaf2f83e8f924d4a70317a2ce4703a49964d6007707949cfa5f5L303-R304","label":"nats-io/nats.rs@817a7b9"},"references":[{"type":"WEB","url":"https://github.com/nats-io/nats.rs/commit/817a7b942c462fa9d9938dcb62124173634132fb#diff-767d442397fcaaf2f83e8f924d4a70317a2ce4703a49964d6007707949cfa5f5L303-R304"},{"type":"PACKAGE","url":"https://github.com/nats-io/nats.rs"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2023-0027.html"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2023-11-08T04:18:50.210490Z"}}