{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "crypto-failure"
        ],
        "cvss": null,
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "async-nats",
        "purl": "pkg:cargo/async-nats"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.29.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "GHSA-f5v5-ccqc-6w36"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "The NATS official Rust clients are vulnerable to MitM when using TLS.\n\nThe common name of the server\u0027s TLS certificate is validated against\nthe `host`name provided by the server\u0027s plaintext `INFO` message\nduring the initial connection setup phase. A MitM proxy can tamper with\nthe `host` field\u0027s value by substituting it with the common name of a\nvalid 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\n   the tampered `INFO` back to the client\n6. The proxy upgrades the client connection to TLS, presenting a certificate issued\n   by a certificate authority present in the client\u0027s keychain.\n   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\n   attacker-controlled value it was given\n9. The client has been fooled by the MitM proxy into accepting the attacker-controlled certificate",
  "id": "RUSTSEC-2023-0027",
  "modified": "2023-06-13T13:10:24Z",
  "published": "2023-03-24T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/async-nats"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2023-0027.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nats-io/nats.rs/commit/817a7b942c462fa9d9938dcb62124173634132fb#diff-767d442397fcaaf2f83e8f924d4a70317a2ce4703a49964d6007707949cfa5f5L303-R304"
    }
  ],
  "related": [],
  "severity": [],
  "summary": "TLS certificate common name validation bypass"
}