This content originally appeared on Bram.us and was authored by Bramus!
This is wild: while writing his own parallel-decodable PNG implementation, David Buchanan discovered he had a bug in his code. Soon after, he found out Apple has the same bug in their implementation which ships.
As a result, it’s possible to craft a PNG in such a way that Apple’s decoder will show a different image. Because Safari delegates the task of decoding images to the OS, all Apple browsers — including MobileSafari — also show the “wrong” image.
If you’re using Apple-flavoured software, you should see “HELLO APPLE”, and on all other software, you should see “HELLO WORLD”.
Here’s a side-by-side comparison:
Because Chrome uses its built-in PNG decoder, it is not affected by this.
David also created a tool to craft your own PNG.
PNG Parser Differential →
Ambiguous PNG Packer →
This content originally appeared on Bram.us and was authored by Bramus!
Bramus! | Sciencx (2021-12-17T00:05:27+00:00) Here’s a PNG that will show a different image in Apple Software. Retrieved from https://www.scien.cx/2021/12/17/heres-a-png-that-will-show-a-different-image-in-apple-software/
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