CVE-2026-84784

{
  "id": "CVE-2026-84784",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-84784",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-29T16:43:47.766260Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "openssl-security@openssl.org",
      "affectedData": [
        {
          "vendor": "OpenSSL",
          "product": "OpenSSL",
          "versions": [
            {
              "status": "affected",
              "version": "4.0.0",
              "lessThan": "4.0.3",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "3.6.0",
              "lessThan": "3.6.5",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "3.5.0",
              "lessThan": "3.5.9",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "3.4.0",
              "lessThan": "3.4.8",
              "versionType": "semver"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-09-29T16:17:12.810",
  "references": [
    {
      "url": "https://github.com/openssl/openssl/commit/4685c914b0d410b1034f40b547c95bc95e7a380a",
      "source": "openssl-security@openssl.org"
    },
    {
      "url": "https://github.com/openssl/openssl/commit/9a30fe0fba195c14e5b87bf93c0d0fdb70373806",
      "source": "openssl-security@openssl.org"
    },
    {
      "url": "https://github.com/openssl/openssl/commit/dba3c48d653c64fcbc9070a17a0ee2b3e2f3af1f",
      "source": "openssl-security@openssl.org"
    },
    {
      "url": "https://github.com/openssl/openssl/commit/e9e5155833fa968bee50024bf9ca3a185ab599fe",
      "source": "openssl-security@openssl.org"
    },
    {
      "url": "https://openssl-library.org/news/secadv/20260929.txt",
      "source": "openssl-security@openssl.org"
    }
  ],
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "openssl-security@openssl.org",
      "description": [
        {
          "lang": "en",
          "value": "CWE-770"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "lastModified": "2026-09-29T21:27:41.130",
  "sourceIdentifier": "openssl-security@openssl.org"
}