CVE-2026-44513

Diffusers is the a library for pretrained diffusion models. Prior to 0.38.0, a trustremotecode bypass in DiffusionPipeline.frompretrained allows arbitrary remote code execution despite the user passing trustremotecode=False (or omitting it, which is the default). The vulnerability has three variants, all sharing the same root cause — the trustremotecode 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.frompretrained('repoA', custompipeline='attacker/repoB', trustremotecode=False) — the gate evaluated against repoA's file list rather than repoB's, so repoB's pipeline.py was loaded and executed. DiffusionPipeline.frompretrained('/local/snapshot', custompipeline='attacker/repoB', trustremotecode=False) — the local-path branch never invoked download(), so the gate was never reached and remote code from repoB executed. DiffusionPipeline.frompretrained('/local/snapshot', trustremotecode=False) where the snapshot contains custom component files (e.g. unet/myunetmodel.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.