RUSTSEC-2026-0217

tract_nnef::tensors::read_tensor builds a tensor shape from attacker-controlled 32-bit dimensions and computes both the element count product(shape) and the byte allocation product(shape) * size_of(dt) with unchecked usize arithmetic. In release builds (no overflow-checks) both products wrap modulo 2^64.

A crafted NNEF .dat tensor can choose dimensions whose wrapped products collapse to a small value that satisfies the header size-consistency check, while the true element count stays astronomically large. read_tensor then returns a Tensor whose reported len (e.g. 2^61 + 7) far exceeds its backing heap allocation (e.g. 56 bytes). The unchecked accessor as_slice_unchecked (slice::from_raw_parts(ptr, self.len())) subsequently yields a slice spanning ~18 EiB over the small buffer.

The out-of-bounds read fires automatically during model build (no inference required), reachable through the default DatLoader resource loader via the public tract_nnef::nnef().model_for_path / model_for_read API when the const-folding as_uniform fast-path materializes the over-long constant. The always-on primitive is a bounded adjacent-heap over-read (information disclosure); access further past the mapped region SIGSEGVs (denial of service). No out-of-bounds write or code execution was demonstrated.

Affected: every release line prior to the backported fixes — < 0.21.16, 0.22.0–0.22.1, and 0.23.0. The block-quant path had already received an analogous blob-size guard; the dense DatLoader path was missed.

Mitigation

Upgrade to 0.21.16, 0.22.2, or 0.23.1. The fix computes the shape product and byte size with checked_mul and rejects the tensor on overflow (commit 34c7df2).