We found a bug in the hyper HTTP library

8 days ago

The Images service, built in Rust on Workers, runs on every machine in Cloudflare's edge network and uses the hyper HTTP library.
In 2025, the Images binding was rearchitected for a more direct connection, but later intermittent failures occurred for larger images with truncated responses.
The bug was a race condition in hyper where a slow reader could cause a premature socket shutdown, losing data; it was fixed with a four-line code change.
Investigation involved distributed tracing, strace syscall analysis, and a custom test to reproduce the bug, leading to a targeted fix in hyper's poll_shutdown.
The fix was contributed upstream to hyper, stabilizing the binding and enabling expanded functionality, including support for hosted images.

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