fix: bound $ref expansion in strict JSON schema conversion - #3838
#3838Merged
seratch merged 1 commit intoJul 15, 2026
openai:mainopenai/openai-agents-python:mainfrom
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Merged
fix: bound $ref expansion in strict JSON schema conversion#3838seratch merged 1 commit intoopenai:mainopenai/openai-agents-python:mainfrom ioleksiuk:fix/strict-schema-ref-expansion-dosioleksiuk/openai-agents-python:fix/strict-schema-ref-expansion-dosCopy head branch name to clipboard
seratch merged 1 commit into
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`_ensure_strict_json_schema` inlines each `$ref` that has sibling keys and re-recurses into the inlined subtree with no cycle detection or expansion limit. A schema whose `$defs` reference the next level twice therefore expands to 2**N nodes: a few-KB schema balloons to hundreds of MB and pins a CPU core. Because the conversion runs synchronously inside the async run loop, an untrusted schema (for example, a tool schema advertised by a third-party MCP server) can stall the event loop (CWE-400 / CWE-674). Thread a shared node-visit budget through the recursion and raise a UserError once it is exhausted. This turns the pathological case into a fast, bounded error while leaving normal schemas unaffected.
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Summary
ensure_strict_json_schema(used for function-tool, output, and MCP tool schemas whenconvert_schemas_to_strictis enabled) inlines every$refthat has sibling keys and then re-recurses into the inlined subtree, with no cycle detection or expansion limit. A schema whose$defsreference the next level twice therefore expands to2**Nnodes:This threads a shared node-visit budget through the recursion. Once the budget is exhausted, conversion raises a
UserErrorinstead of expanding unbounded, turning the pathological case into a fast, bounded error. Normal schemas are orders of magnitude below the limit and are unaffected.Test plan
test_ref_expansion_bomb_is_rejected: a 30-level$reffan-out (which would inline to2**30nodes) now raisesUserErrorin milliseconds instead of exhausting CPU/memory.$refinlining, chained refs, unions, etc.) are unchanged and pass.make format,make lint,make typecheck, andmake testspass locally.Issue number
N/A
Checks
.agents/skills/code-change-verification/scripts/run.sh