rustsec-2025-0004
Vulnerability from osv_rustsec
Published
2025-02-02 12:00
Modified
2025-10-28 06:02
Summary
ssl::select_next_proto use after free
Details

In openssl versions before 0.10.70, ssl::select_next_proto can return a slice pointing into the server argument's buffer but with a lifetime bound to the client argument. In situations where the server buffer's lifetime is shorter than the client buffer's, this can cause a use after free. This could cause the server to crash or to return arbitrary memory contents to the client.

openssl 0.10.70 fixes the signature of ssl::select_next_proto to properly constrain the output buffer's lifetime to that of both input buffers.

In standard usage of ssl::select_next_proto in the callback passed to SslContextBuilder::set_alpn_select_callback, code is only affected if the server buffer is constructed within the callback. For example:

Not vulnerable - the server buffer has a 'static lifetime:

builder.set_alpn_select_callback(|_, client_protos| {
    ssl::select_next_proto(b"\x02h2", client_protos).ok_or_else(AlpnError::NOACK)
});

Not vulnerable - the server buffer outlives the handshake:

let server_protos = b"\x02h2".to_vec();
builder.set_alpn_select_callback(|_, client_protos| {
    ssl::select_next_proto(&server_protos, client_protos).ok_or_else(AlpnError::NOACK)
});

Vulnerable - the server buffer is freed when the callback returns:

builder.set_alpn_select_callback(|_, client_protos| {
    let server_protos = b"\x02h2".to_vec();
    ssl::select_next_proto(&server_protos, client_protos).ok_or_else(AlpnError::NOACK)
});
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "memory-exposure"
        ],
        "cvss": null,
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "openssl::ssl::select_next_proto"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "openssl",
        "purl": "pkg:cargo/openssl"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.10.70"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2025-24898",
    "GHSA-rpmj-rpgj-qmpm"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "In `openssl` versions before `0.10.70`, `ssl::select_next_proto` can return a slice pointing into the `server` argument\u0027s buffer but with a lifetime bound to the `client` argument. In situations where the `server` buffer\u0027s lifetime is shorter than the `client` buffer\u0027s, this can cause a use after free. This could cause the server to crash or to return arbitrary memory contents to the client.\n\n`openssl` 0.10.70 fixes the signature of `ssl::select_next_proto` to properly constrain the output buffer\u0027s lifetime to that of both input buffers.\n\nIn standard usage of `ssl::select_next_proto` in the callback passed to `SslContextBuilder::set_alpn_select_callback`, code is only affected if the `server` buffer is constructed *within* the callback. For example:\n\nNot vulnerable - the server buffer has a `\u0027static` lifetime:\n```rust\nbuilder.set_alpn_select_callback(|_, client_protos| {\n    ssl::select_next_proto(b\"\\x02h2\", client_protos).ok_or_else(AlpnError::NOACK)\n});\n```\n\nNot vulnerable - the server buffer outlives the handshake:\n```rust\nlet server_protos = b\"\\x02h2\".to_vec();\nbuilder.set_alpn_select_callback(|_, client_protos| {\n    ssl::select_next_proto(\u0026server_protos, client_protos).ok_or_else(AlpnError::NOACK)\n});\n```\n\nVulnerable - the server buffer is freed when the callback returns:\n```rust\nbuilder.set_alpn_select_callback(|_, client_protos| {\n    let server_protos = b\"\\x02h2\".to_vec();\n    ssl::select_next_proto(\u0026server_protos, client_protos).ok_or_else(AlpnError::NOACK)\n});\n```",
  "id": "RUSTSEC-2025-0004",
  "modified": "2025-10-28T06:02:18Z",
  "published": "2025-02-02T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/openssl"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2025-0004.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/sfackler/rust-openssl/security/advisories/GHSA-rpmj-rpgj-qmpm"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sfackler/rust-openssl/pull/2360"
    }
  ],
  "related": [],
  "severity": [],
  "summary": "ssl::select_next_proto use after free"
}


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