Outgoing datagram buffer accounting can panic the sender in quinn-proto

{
  "id": "472b0c537f69a0f9dbe64c20b30f7bcc3ff4d439fc7868b3c3a3c2802347f3e2",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0343",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Outgoing datagram buffer accounting can panic the sender in quinn-proto",
    "summary": "The limit on memory used to buffer outgoing datagrams, introduced in 0.11.17, subtracted an evicted datagram's size from the buffered byte counter twice when `Datagrams::send` was called with `drop = true` (as `Connection::send_datagram` in the `quinn` crate does) while the buffer was full. Under sustained eviction the counter drifts below its true value: debug builds panic with an integer underflow, while release builds wrap the counter, drain the whole queue, and then panic on a desynchronization check in a later `send` call. In `quinn`, this panic occurs while the connection lock is held, poisoning it and causing a double panic (and thus an abort) when the connection is dropped. This can be triggered without a malicious peer, by an application that sends a burst of datagrams and then idles. It can also be triggered by a peer that keeps the connection alive with PING frames while withholding acknowledgements, so that the sender's congestion window stays closed and the outgoing queue never drains. Applications that use `send_datagram_wait` are not affected. Only 0.11.17 is affected; the flaw was corrected in 0.11.18 by removing the redundant subtraction. Thanks to [@alexpyattaev](https://github.com/alexpyattaev) for reporting and [@vcarus](https://github.com/vcarus) for fixing this issue.",
    "evidence": "osv:RUSTSEC-2026-0343",
    "products": [
      {
        "name": {
          "value": "quinn-proto",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.11.18",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "RUSTSEC-2026-0343",
      "aliases": [
        "GHSA-ppcp-v39w-8jq2",
        "RUSTSEC-2026-0343"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.11.17"
                },
                {
                  "fixed": "0.11.18"
                }
              ]
            }
          ],
          "package": {
            "name": "quinn-proto",
            "purl": "pkg:cargo/quinn-proto",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0343.json",
            "categories": [
              "denial-of-service"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:15:01.961745820Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/quinn-proto",
        "https://rustsec.org/advisories/RUSTSEC-2026-0343.html",
        "https://github.com/quinn-rs/quinn/pull/2806"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306470,
  "published_at": "2026-09-14T12:00:00+00:00"
}