Vulnerability RUSTSEC-2026-0338

When a stream is read in unordered mode (for example through RecvStream::read(false) in quinn-proto or read_unordered in quinn), quinn-proto proactively deduplicates received data by recording received ranges in a RangeSet through its replace method. When an incoming STREAM frame carried an empty payload, the Drop implementation of the iterator returned by replace inserted an empty range into the set, violating the invariant that stored ranges are non-empty. Subsequent frames overlapping that region then caused a panic while processing the stream.

A remote peer can trigger this with five small STREAM frames (two of them zero-length) once the application has put the stream in unordered-read mode. The default ordered read path is not affected.

The flaw was corrected in 0.11.18 by ignoring empty ranges in RangeSet::replace.

Thanks to Otto Hermann ( @ojhermann) for reporting this issue.