{"schema":"record/v1","id":"art_01M5P4AJ86GZ51ZXSZJB2FT915","type":"article","revision":1,"etag":"\"r1.s0\"","title":"What does --enable-cors-header actually do, and does enabling it weaken the built-in origin check?","summary":"Problem. People add --enable-cors-header to let a web front end call ComfyUI. Conditions. Any start with the flag. Method. The flag takes one optional origin string (bare flag means '*'). Server.py chooses between two middlewares: if the flag is set it installs the CORS middleware, otherwise the origin-only middleware, so enabling CORS removes the Sec-Fetch-Site and Host/Origin 403 checks entirely. The CORS middleware answers every OPTIONS request with success and sets Allow-Origin to the configured string verbatim, Allow-Credentials true, and Allow-Headers including Authorization. Failure modes. No allowlist or per-request origin validation: a single static value; with '*' any page can drive the API (browsers refuse credentialed wildcard requests, but ComfyUI has no cookies to protect, so cross-origin simple requests can still queue work: inference). Limitations. Prefer a specific origin; put authentication in a proxy. Version. Commit fb3befd.","status":"active","body":{"text":"Problem. People add --enable-cors-header to let a web front end call ComfyUI. Conditions. Any start with the flag. Method. The flag takes one optional origin string (bare flag means '*'). Server.py chooses between two middlewares: if the flag is set it installs the CORS middleware, otherwise the origin-only middleware, so enabling CORS removes the Sec-Fetch-Site and Host/Origin 403 checks entirely. The CORS middleware answers every OPTIONS request with success and sets Allow-Origin to the configured string verbatim, Allow-Credentials true, and Allow-Headers including Authorization. Failure modes. No allowlist or per-request origin validation: a single static value; with '*' any page can drive the API (browsers refuse credentialed wildcard requests, but ComfyUI has no cookies to protect, so cross-origin simple requests can still queue work: inference). Limitations. Prefer a specific origin; put authentication in a proxy. Version. Commit fb3befd.\n\nCurator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.\n\nLimitations: Code reading only; the if/else structure was read from adjacent lines (E2 is the else branch). Browser CORS enforcement details not tested.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://raw.githubusercontent.com/comfyanonymous/ComfyUI/fb3befd168731438f88bc96e0920a538e8649878/comfy/cli_args.py","note":"cli_args.py --enable-cors-header; PromptServer.__init__; create_cors_middleware; create_cors_middleware; reasoning over R2 code"},{"url":"https://raw.githubusercontent.com/comfyanonymous/ComfyUI/fb3befd168731438f88bc96e0920a538e8649878/server.py","note":"cli_args.py --enable-cors-header; PromptServer.__init__; create_cors_middleware; create_cors_middleware; reasoning over R2 code"}]},"categories":["T08","T09","T20"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://raw.githubusercontent.com/comfyanonymous/ComfyUI/fb3befd168731438f88bc96e0920a538e8649878/comfy/cli_args.py","claim":"Problem. 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Commit fb3befd.\n\nCurator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.\n\nLimitations: Code reading only; the if/else structure was read from adjacent lines (E2 is the else branch). Browser CORS enforcement details not tested.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://raw.githubusercontent.com/comfyanonymous/ComfyUI/fb3befd168731438f88bc96e0920a538e8649878/comfy/cli_args.py","note":"cli_args.py --enable-cors-header; PromptServer.__init__; create_cors_middleware; create_cors_middleware; reasoning over R2 code"},{"url":"https://raw.githubusercontent.com/comfyanonymous/ComfyUI/fb3befd168731438f88bc96e0920a538e8649878/server.py","note":"cli_args.py --enable-cors-header; PromptServer.__init__; create_cors_middleware; create_cors_middleware; reasoning over R2 code"}]},"tags":[],"type":"article","links":[],"title":"What does --enable-cors-header actually do, and does enabling it weaken the built-in origin check?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"Problem. 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