Ray: Remote Code Execution via Parquet Arrow Extension Type Deserialization

Ray Data registers custom Arrow extension types (`ray.data.arrow_tensor`, `ray.data.arrow_tensor_v2`, `ray.data.arrow_variable_shaped_tensor`) globally in PyArrow. When PyArrow reads a Parquet file containing one of these extension types, it calls `__arrow_ext_deserialize__` on the field's metadata bytes. Ray's implementation passes these bytes directly to `cloudpickle.loads()`, achieving arbitrary code execution during schema parsing, before any row data is read. In May 2024, Ray fixed a related vulnerability in `PyExtensionType`-based extension types ([issue #41314](https://github.com/ray-project/ray/issues/41314), [PR #45084](https://github.com/ray-project/ray/pull/45084)). In July 2025, [PR #54831](https://github.com/ray-project/ray/pull/54831) introduced `cloudpickle.loads()` into the replacement extension types' deserialization path, reintroducing the same class of vulnerability. ## Impact - **Affected versions**: Ray 2.49.0 through 2.54.0 (latest release as of March 2026). The vulnerable `_deserialize_with_fallback` function with `cloudpickle.loads()` was introduced in commit `f6d21db1a4` ([PR #54831](https://github.com/ray-project/ray/pull/54831), July 2025), first released in Ray 2.49.0. - **Affected configurations**: Any process that uses Ray Data and reads Parquet files. The extension types are registered globally in PyArrow, so all Parquet reads in the process are affected, including `ray.data.read_parquet()`, `pyarrow.parquet.read_table()`, `pandas.read_parquet()`, etc. - **Attacker prerequisites**: The attacker must place a crafted Parquet file where a Ray Data pipeline reads it. No authentication or cluster access is required. The Parquet file must contain a column with a `ray.data.arrow_tensor` (or v2, or variable-shaped) extension type name, which makes this a targeted attack against Ray Data users.

CVSS 4.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Severity from

GitHub (reviewed advisory)

Weakness

CWE-502, CWE-94

Also known as

CVE-2026-41486, PYSEC-2026-2272, PYSEC-2026-2296

• github.com/ray-project/ray/security/advisories/GHSA-mw35-8rx3-xf9r
• nvd.nist.gov/vuln/detail/CVE-2026-41486
• github.com/ray-project/ray/pull/54831
• github.com/ray-project/ray/pull/62056
• github.com/ray-project/ray/commit/c02bd31ae31996805868baa446a131a8d304525f
• github.com/ray-project/ray
• github.com/ray-project/ray/releases/tag/ray-2.55.0