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crossorigin="anonymous" Prevents Rendering and Canvas Access for Custom Scheme and HTTP Images on iOS 18
On iOS 18, when setting the src attribute of an tag to a custom scheme (e.g., myapp://image.png) or an HTTP URL (http://example.com/image.png), if crossorigin="anonymous" is applied, the image fails to load. Additionally, images affected by this issue cannot be drawn to a , as the browser treats them as tainted and blocks access to their pixel data. This issue did not occur in previous iOS versions and seems to be a regression in iOS 18. Steps to Reproduce: Open an HTTPS-hosted H5 page in Safari on iOS 18. Add an tag with crossorigin="anonymous" and set src to either: A custom scheme: <img src="myapp://image.png" crossorigin="anonymous"> An HTTP URL (even from the same origin): <img src="http://example.com/image.png" crossorigin="anonymous"> Observe that the image does not load. Attempt to draw the image onto a and retrieve its data: const canvas = document.createElement("canvas"); const ctx = canvas.getContext("2d"); const img = new Image(); img.crossOrigin = "anonymous"; img.src = "http://example.com/image.png"; // or "myapp://image.png" img.onload = () => { ctx.drawImage(img, 0, 0); try { console.log(canvas.toDataURL()); // Expect base64 image data } catch (error) { console.error("Canvas is tainted:", error); } }; Notice that the image is blocked, and any attempt to access pixel data results in a CORS error. Expected Behavior: * The image should be displayed if it is accessible under normal CORS rules. * The API should allow access to the image data unless explicitly blocked by the server’s CORS policy. Actual Behavior: The image fails to load when crossorigin="anonymous" is applied. The API does not allow access to the image data, treating it as tainted. Removing crossorigin="anonymous" allows the image to display in some cases, but this is not a viable workaround when CORS enforcement is required. Regression: Works correctly on: iOS 17 and earlier Broken on: iOS 18 Environment: Device: iPhone/iPad iOS Version: 18.0+ Browser: Safari Suggested Fix: Apple should investigate this regression and allow custom schemes and HTTP images to be correctly handled under CORS policies when crossorigin="anonymous" is set. If the source allows cross-origin requests, Safari should not block the image or its use in .
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