Unsloth Zoo versions 2025.9.9 before 2026.8.14, as implemented in Unsloth 2025.9.9 through…

Why it is Amber

• CVSS 8.1 high
• Remotely exploitable without logging in

References

• https://github.com/unslothai/unsloth-zoo/pull/1083
• https://github.com/unslothai/unsloth-zoo/pull/1108
• https://github.com/unslothai/unsloth/commit/92ee0207a38ebc8af1a0e678aa92d7e7d901ea0d
• https://www.vulncheck.com/advisories/unsloth-zoo-code-injection-via-model-type-in-config-json

Original 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.