{"id":"GHSA-98h9-4798-4q5v","summary":"Diffusers has a `trust_remote_code` bypass via `custom_pipeline` and local custom components","details":"### Impact\n\nA `trust_remote_code` bypass in `DiffusionPipeline.from_pretrained` allows arbitrary remote code execution despite the user passing `trust_remote_code=False` (or omitting it, which is the default). The vulnerability has three variants, all sharing the same root cause — the `trust_remote_code` gate was implemented inside `DiffusionPipeline.download()` rather than at the actual dynamic-module load site, so any code path that bypassed or short-circuited `download()` also bypassed the security check:\n\n1. **Cross-repo `custom_pipeline`.** `DiffusionPipeline.from_pretrained('repoA', custom_pipeline='attacker/repoB', trust_remote_code=False)` — the gate evaluated against `repoA`'s file list rather than `repoB`'s, so `repoB`'s `pipeline.py` was loaded and executed.\n2. **Local snapshot + Hub `custom_pipeline`.** `DiffusionPipeline.from_pretrained('/local/snapshot', custom_pipeline='attacker/repoB', trust_remote_code=False)` — the local-path branch never invoked `download()`, so the gate was never reached and remote code from `repoB` executed.\n3. **Local snapshot with custom components.** `DiffusionPipeline.from_pretrained('/local/snapshot', trust_remote_code=False)` where the snapshot contains custom component files (e.g. `unet/my_unet_model.py`) referenced from `model_index.json` — same root cause; the local path skipped `download()` and custom component code executed.\n\nSilent remote code execution on the victim's machine. Anyone calling `DiffusionPipeline.from_pretrained` with custom pipelines is impacted.\n\n### Patches\n\nYes. Fixed in **diffusers 0.38.0** via [PR #13448](https://github.com/huggingface/diffusers/pull/13448). All users on versions `\u003c 0.38.0` should upgrade:\n\n```bash\npip install --upgrade \"diffusers\u003e=0.38.0\"\n```\n\nThe fix moves the `trust_remote_code` gate out of `DiffusionPipeline.download()` and into `get_cached_module_file` in `src/diffusers/utils/dynamic_modules_utils.py`, which is the actual chokepoint for every dynamic module load (local, Hub, or community mirror). All three variants now raise `ValueError` instead of executing untrusted code.\n\n### Workarounds\n\nIf upgrading immediately is not possible:\n\n- Only call `from_pretrained` with `pretrained_model_name_or_path`, `custom_pipeline`, and local snapshot directories from fully trusted sources that have been audited.\n- Do not pass `custom_pipeline=` pointing at a Hub repository different from the primary `pretrained_model_name_or_path` before reading its `pipeline.py`.\n- Before calling `from_pretrained` on a local snapshot, inspect the snapshot for unexpected `*.py` files, especially under component subdirectories (`unet/`, `scheduler/`, etc.) and at the snapshot root.\n\nThese are mitigations, not fixes — the only complete remediation is upgrading to 0.38.0.\n\n### Resources\n\n- **Fix:** https://github.com/huggingface/diffusers/pull/13448\n- **Original issue:** https://github.com/huggingface/diffusers/issues/13446\n- **Release notes:** https://github.com/huggingface/diffusers/releases/tag/v0.38.0\n- **CWE-94:** https://cwe.mitre.org/data/definitions/94.html","aliases":["CVE-2026-44513","PYSEC-2026-40"],"modified":"2026-09-10T03:51:05.118401784Z","published":"2026-05-07T05:31:17Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-05-07T05:31:17Z","nvd_published_at":"2026-05-14T17:16:22Z","cwe_ids":["CWE-94"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/huggingface/diffusers/security/advisories/GHSA-98h9-4798-4q5v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44513"},{"type":"WEB","url":"https://github.com/huggingface/diffusers/issues/13446"},{"type":"WEB","url":"https://github.com/huggingface/diffusers/pull/13448"},{"type":"WEB","url":"https://github.com/huggingface/diffusers/commit/a37f6f8394ac2a7ee8360c3abea811efe54512b1"},{"type":"PACKAGE","url":"https://github.com/huggingface/diffusers"},{"type":"WEB","url":"https://github.com/huggingface/diffusers/releases/tag/v0.38.0"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/diffusers/PYSEC-2026-40.yaml"}],"affected":[{"package":{"name":"diffusers","ecosystem":"PyPI","purl":"pkg:pypi/diffusers"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.38.0"}]}],"versions":["0.0.1","0.0.2","0.0.3","0.0.4","0.1.0","0.1.1","0.1.2","0.1.3","0.10.0","0.10.1","0.10.2","0.11.0","0.11.1","0.12.0","0.12.1","0.13.0","0.13.1","0.14.0","0.15.0","0.15.1","0.16.0","0.16.1","0.17.0","0.17.1","0.18.0","0.18.1","0.18.2","0.19.0","0.19.1","0.19.2","0.19.3","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.20.0","0.20.1","0.20.2","0.21.0","0.21.1","0.21.2","0.21.3","0.21.4","0.22.0","0.22.1","0.22.2","0.22.3","0.23.0","0.23.1","0.24.0","0.25.0","0.25.1","0.26.0","0.26.1","0.26.2","0.26.3","0.27.0","0.27.1","0.27.2","0.28.0","0.28.1","0.28.2","0.29.0","0.29.1","0.29.2","0.3.0","0.30.0","0.30.1","0.30.2","0.30.3","0.31.0","0.32.0","0.32.1","0.32.2","0.33.0","0.33.1","0.34.0","0.35.0","0.35.1","0.35.2","0.36.0","0.37.0","0.37.1","0.4.0","0.4.1","0.4.2","0.5.0","0.5.1","0.6.0","0.7.0","0.7.1","0.7.2","0.8.0","0.8.1","0.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-98h9-4798-4q5v/GHSA-98h9-4798-4q5v.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"}]}