{"id":"CVE-2026-44827","summary":"Diffusers: None.py Trust Remote Code Bypass","details":"Diffusers is the a library for  pretrained diffusion models. Prior to 0.38.0, diffusers 0.37.0 allows remote code execution without the trust_remote_code=True safeguard when loading pipelines from Hugging Face Hub repositories. The _resolve_custom_pipeline_and_cls function in pipeline_loading_utils.py performs string interpolation on the custom_pipeline parameter using f\"{custom_pipeline}.py\". When custom_pipeline is not supplied by the user, it defaults to None, which Python interpolates as the literal string \"None.py\". If an attacker publishes a Hub repository containing a file named None.py with a class that subclasses DiffusionPipeline, the file is automatically downloaded and executed during a standard DiffusionPipeline.from_pretrained() call with no additional keyword arguments. The trust_remote_code check in DiffusionPipeline.download() is bypassed because it evaluates custom_pipeline is not None as False (since the kwarg was never supplied), while the downstream code path that actually loads the module resolves the None value into a valid filename. An attacker can achieve silent arbitrary code execution by publishing a malicious model repository with a None.py file and a standard-looking model_index.json that references a legitimate pipeline class name, requiring only that a victim calls from_pretrained on the repository. This vulnerability is fixed in 0.38.0.","aliases":["GHSA-j7w6-vpvq-j3gm","PYSEC-2026-41"],"modified":"2026-08-12T03:51:22.044152471Z","published":"2026-05-14T16:33:42.373Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-94"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44827.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44827.json"},{"type":"ADVISORY","url":"https://github.com/huggingface/diffusers/security/advisories/GHSA-j7w6-vpvq-j3gm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44827"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/huggingface/diffusers","events":[{"introduced":"0"},{"fixed":"275869dcae4ebcfee6a80253fdabc56033335020"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"0.38.0"}],"source":["AFFECTED_FIELD","CPE_RANGE"],"cpe":"cpe:2.3:a:huggingface:diffusers:*:*:*:*:*:python:*:*"}}],"versions":["v0.16.0","v0.15.0","v0.14.0","v0.13.0","v0.12.0","v0.11.0","v0.10.0","v0.9.0","v0.8.0","v0.7.0","v0.6.0","v0.5.0","v0.4.1","v0.4.0","v0.3.0","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0","0.1.3","0.1.2","0.1.1","0.1.0","v0.0.4","v0.0.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-44827.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"}]}