Advisories

Unsloth Zoo Code Injection via model_type in config.json

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severity
high
date
Affecting
  • unsloth-zoo >= 2025.9.9, < 2026.8.14

  • unsloth >= 2025.9.9, < 2026.8.20

CWE
  • CWE-94 Improper Control of Generation of Code ('Code Injection')
CVSS
8.6
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Credit
Ariel Fogel (afogel) of Pillar Security
Description
Unsloth Zoo versions 2025.9.9 before 2026.8.14, as implemented in Unsloth 2025.9.9 through 2026.8.19, contains a code injection vulnerability in the model-loading compile path where the get_transformers_model_type() function in hf_utils.py collects model_type values from nested model configurations without enforcing a character allowlist, allowing newlines and arbitrary Python source to survive normalization. Attackers can embed a newline in a nested model_type value within a malicious model's config.json to terminate the generated import statement and execute arbitrary Python code via exec() in unsloth_compile_transformers(), achieving remote code execution as the loading user when the model is loaded for training or inference.

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