{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "4.0.0"
              },
              {
                "fixed": "4.0.3"
              },
              {
                "introduced": "3.6.0"
              },
              {
                "fixed": "3.6.5"
              },
              {
                "introduced": "3.5.0"
              },
              {
                "fixed": "3.5.9"
              },
              {
                "introduced": "3.4.0"
              },
              {
                "fixed": "3.4.8"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "11b7b6ea3b65a584e1d31408ed1bdb139465cffd"
            },
            {
              "introduced": "7b371d80d959ec9ab4139d09d78e83c090de9779"
            },
            {
              "introduced": "636dfadc70ce26f2473870570bfd9ec352806b1d"
            },
            {
              "introduced": "98acb6b02839c609ef5b837794e08d906d965335"
            },
            {
              "fixed": "af1775b60dfa141a4ad762585052cabeb9f37e9e"
            },
            {
              "fixed": "c8bd5a57108599ac650bbae77fcabe3109dab2e8"
            },
            {
              "fixed": "45e844fa2a14ec92d146bd8f5778ac130b6625fb"
            },
            {
              "fixed": "e72c946f6f6d94c8ba5119acb25340b7b6b2073f"
            },
            {
              "fixed": "4685c914b0d410b1034f40b547c95bc95e7a380a"
            },
            {
              "fixed": "9a30fe0fba195c14e5b87bf93c0d0fdb70373806"
            },
            {
              "fixed": "dba3c48d653c64fcbc9070a17a0ee2b3e2f3af1f"
            },
            {
              "fixed": "e9e5155833fa968bee50024bf9ca3a185ab599fe"
            }
          ],
          "repo": "https://github.com/openssl/openssl",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "openssl",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84784.json"
  },
  "details": "Issue summary: A malicious remote peer may flood the local QUIC\nstack with NEW_CONNECTION_ID frames by avoiding a limit check on\nhow many connection IDs the remote QUIC stack can use.\n\nImpact summary: The local QUIC stack sends a RETIRE_CONN_ID frame\nfor every NEW_CONNECTION_ID frame it receives. The RETIRE_CONN_ID\nframe is dispatched via the Control Frame Queue (CFQ). If the remote\npeer also withholds ACKs, then it can force the local stack\nto allocate ~400MB (depending on ACK delay).\n\nCWE: CWE-770: Allocation of Resources Without Limits or Throttling\n\nDescription: RFC 9000 sections 5.1.1 and 5.1.2 [1] describe the mechanism\nby which a remote peer can notify the local QUIC stack to change the\ndestination connection ID (a.k.a. CID) the local stack uses to\nidentify the connection at the remote peer. Each CID is associated\nwith a sequence number. The sequence number is transmitted\nin NEW_CONNECTION_ID and RETIRE_CONNECTION_ID frames to identify the CID\nwhich is being either associated with a connection or retired.\n\nThe remote peer sends a NEW_CONNECTION_ID frame to let the local stack know\na new CID is being associated with an existing connection. The\nNEW_CONNECTION_ID frame carries the new CID, its sequence number, and the\nretire-prior-to number. The retire-prior-to identifies existing\nCIDs that are to be retired. The local QUIC stack must send a\nRETIRE_CONNECTION_ID for every destination CID whose sequence number\nis less than retire-prior-to. The CID becomes retired after the\nlocal stack receives an ACK for its RETIRE_CONNECTION_ID frame.\n\nAlthough the OpenSSL QUIC stack supports at most one destination CID\nfor every connection, it can be tricked into processing more than\none RETIRE_CONNECTION_ID frame per connection. The OpenSSL QUIC\nstack currently retires the destination CID as soon as it receives\nthe NEW_CONNECTION_ID, while in fact the destination CID must\nbe retired after an ACK for the RETIRE_CONNECTION_ID frame is received.\nCorrecting the flawed logic also fixes the backlog growth.\n\n[1] https://datatracker.ietf.org/doc/html/rfc9000#name-issuing-connection-ids\n\nFIPS impact: no\nThe FIPS module is not affected as the QUIC implementation is outside of\nthe OpenSSL FIPS module boundary.",
  "id": "CVE-2026-84784",
  "modified": "2026-10-01T03:30:40.941747423Z",
  "published": "2026-09-29T15:32:25.758Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84784.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84784"
    },
    {
      "type": "ADVISORY",
      "url": "https://openssl-library.org/news/secadv/20260929.txt"
    },
    {
      "type": "FIX",
      "url": "https://github.com/openssl/openssl/commit/4685c914b0d410b1034f40b547c95bc95e7a380a"
    },
    {
      "type": "FIX",
      "url": "https://github.com/openssl/openssl/commit/9a30fe0fba195c14e5b87bf93c0d0fdb70373806"
    },
    {
      "type": "FIX",
      "url": "https://github.com/openssl/openssl/commit/dba3c48d653c64fcbc9070a17a0ee2b3e2f3af1f"
    },
    {
      "type": "FIX",
      "url": "https://github.com/openssl/openssl/commit/e9e5155833fa968bee50024bf9ca3a185ab599fe"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "QUIC: Unbounded RETIRE_CONNECTION_ID Backlog"
}