PYSEC-2026-1856

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PYSEC-2026-1856

Summary: PyTorch Vulnerable to Remote Code Execution via Untrusted Checkpoint Files

Details: ### Summary A vulnerability in PyTorch's `weights_only` unpickler allows an attacker to craft a malicious checkpoint file (`.pth`) that, when loaded with `torch.load(..., weights_only=True)`, can corrupt memory and potentially lead to arbitrary code execution. ### Vulnerability Details The `weights_only=True` unpickler failed to properly validate pickle opcodes and storage metadata, allowing: 1. **Heap memory corruption** via `SETITEM`/`SETITEMS` opcodes applied to non-dictionary types 2. **Storage size mismatch** between declared element count and actual data in the archive ### Impact An attacker who can convince a user to load a malicious checkpoint file may achieve arbitrary code execution in the context of the victim's process. # Credit Ji'an Zhou

References: https://github.com/pytorch/pytorch/security/advisories/GHSA-63cw-57p8-fm3p, https://nvd.nist.gov/vuln/detail/CVE-2026-24747, https://github.com/pytorch/pytorch/issues/163105, https://github.com/pytorch/pytorch, https://github.com/pytorch/pytorch/163122/commit/954dc5183ee9205cbe79876ad05dd2d9ae752139, https://github.com/pytorch/pytorch/releases/tag/v2.10.0, https://pypi.org/project/pytorch, https://github.com/advisories/GHSA-63cw-57p8-fm3p