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Isabel Wu 977f663cb0 fix(trl): disable inline GRPO reward code by default (RCE, #11015) (#11068)
fix(trl): disable inline GRPO reward code by default (RCE)

POST /api/fine-tuning/jobs accepts reward_functions[].code, an inline Python
body, and compile_inline_reward() execs it against a restricted-builtins
allowlist (_SAFE_BUILTINS). That allowlist is not a security boundary:
().__class__.__bases__[0].__subclasses__() reaches os._wrap_close and thus
os.system, giving arbitrary code execution. The fine-tuning endpoint is
unauthenticated by default, so any caller could run code on the host.

Hardening the allowlist is a losing game against CPython introspection, so
inline reward code is now refused unless the operator explicitly opts in with
LOCALAI_TRL_ALLOW_INLINE_REWARD=true on the backend. Builtin reward functions
are unaffected. The gate lives in build_reward_functions(), the single point
all inline specs flow through. Docs updated to stop describing the allowlist as
a sandbox and to document the opt-in.

Fixes #11015

Signed-off-by: Isabel Wu <231155141+wuisabel-gif@users.noreply.github.com>
Co-authored-by: Isabel Wu <231155141+wuisabel-gif@users.noreply.github.com>
2026-07-23 23:10:34 +02:00
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