PYSEC-2026-40
Vulnerability from pysec - Published: 2026-05-14 17:16 - Updated: 2026-05-20 09:18Diffusers is the a library for pretrained diffusion models. Prior to 0.38.0, a 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. 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. 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. 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. This vulnerability is fixed in 0.38.0.
| Name | purl | diffusers | pkg:pypi/diffusers |
|---|
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "diffusers",
"purl": "pkg:pypi/diffusers"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.38.0"
}
],
"type": "ECOSYSTEM"
}
],
"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"
]
}
],
"aliases": [
"CVE-2026-44513",
"GHSA-98h9-4798-4q5v"
],
"details": "Diffusers is the a library for pretrained diffusion models. Prior to 0.38.0, a 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 \u2014 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. DiffusionPipeline.from_pretrained(\u0027repoA\u0027, custom_pipeline=\u0027attacker/repoB\u0027, trust_remote_code=False) \u2014 the gate evaluated against repoA\u0027s file list rather than repoB\u0027s, so repoB\u0027s pipeline.py was loaded and executed. DiffusionPipeline.from_pretrained(\u0027/local/snapshot\u0027, custom_pipeline=\u0027attacker/repoB\u0027, trust_remote_code=False) \u2014 the local-path branch never invoked download(), so the gate was never reached and remote code from repoB executed. DiffusionPipeline.from_pretrained(\u0027/local/snapshot\u0027, trust_remote_code=False) where the snapshot contains custom component files (e.g. unet/my_unet_model.py) referenced from model_index.json \u2014 same root cause; the local path skipped download() and custom component code executed. This vulnerability is fixed in 0.38.0.",
"id": "PYSEC-2026-40",
"modified": "2026-05-20T09:18:56.669156Z",
"published": "2026-05-14T17:16:22.903Z",
"references": [
{
"type": "EVIDENCE",
"url": "https://github.com/huggingface/diffusers/security/advisories/GHSA-98h9-4798-4q5v"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
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