GHSA-4vr9-8cjf-vf9c Async-h1 request smuggling possible with long unread bodies

• crates.io async-h1: < 2.3.0 → fixed in 2.3.0

Impact This vulnerability affects any webserver that uses async-h1 behind a reverse proxy, including all such Tide applications. If the server does not read the body of a request which is longer than some buffer length, async-h1 will attempt to read a subsequent request from the body content starting at that offset into the body. One way to exploit this vulnerability would be for an adversary to craft a request such that the body contains a request that would not be noticed by a reverse proxy, allowing it to forge forwarded/x-forwarded headers. If an application trusted the authenticity of these headers, it could be misled by the smuggled request. Another potential concern with this vulnerability is that if a reverse proxy is sending multiple http clients' requests along the same keep-alive connection, it would be possible for the smuggled request to specify a long content and capture another user's request in its body. This content could be captured in a post request to an endpoint that allows the content to be subsequently retrieved by the adversary. Patches This has been addressed in async-h1 2.3.0 and previous versions have been yanked. Workarounds none References https://github.com/http-rs/async-h1/releases/tag/v2.3.0 For more information If you have any questions or comments about this advisory: • Open an issue in async-h1 • Contact a core team member on zulip or discord