{"id":"RUSTSEC-2026-0343","aliases":["GHSA-ppcp-v39w-8jq2"],"title":"Outgoing datagram buffer accounting can panic the sender in quinn-proto","summary":"Outgoing datagram buffer accounting can panic the sender in quinn-proto","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"quinn-proto","product":"quinn-proto","ecosystem":"rust","affected":["quinn-proto >= 0.11.17, < 0.11.18"],"patched":["quinn-proto 0.11.18"],"published":"2026-09-14","updated":"2026-10-12","sourceUpdated":"2026-10-12T18:15:01.961745820Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0343","references":[{"url":"https://crates.io/crates/quinn-proto"},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0343.html"},{"url":"https://github.com/quinn-rs/quinn/pull/2806"}],"tags":["osv","rust"],"ingestedAt":"2026-10-13T11:45:30.201Z","slug":"RUSTSEC-2026-0343","body":"## Overview\n\nThe limit on memory used to buffer outgoing datagrams, introduced in 0.11.17, subtracted an\nevicted datagram's size from the buffered byte counter twice when `Datagrams::send` was called\nwith `drop = true` (as `Connection::send_datagram` in the `quinn` crate does) while the buffer was\nfull. Under sustained eviction the counter drifts below its true value: debug builds panic with an\ninteger underflow, while release builds wrap the counter, drain the whole queue, and then panic on\na desynchronization check in a later `send` call. In `quinn`, this panic occurs while the\nconnection lock is held, poisoning it and causing a double panic (and thus an abort) when the\nconnection is dropped.\n\nThis can be triggered without a malicious peer, by an application that sends a burst of datagrams\nand then idles. It can also be triggered by a peer that keeps the connection alive with PING frames\nwhile withholding acknowledgements, so that the sender's congestion window stays closed and the\noutgoing queue never drains. Applications that use `send_datagram_wait` are not affected.\n\nOnly 0.11.17 is affected; the flaw was corrected in 0.11.18 by removing the redundant subtraction.\n\nThanks to [@alexpyattaev](https://github.com/alexpyattaev) for reporting and\n[@vcarus](https://github.com/vcarus) for fixing this issue.\n\n## Affected packages\n\n- `quinn-proto >= 0.11.17, < 0.11.18`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `quinn-proto 0.11.18`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}