HighFix available

mptcp: allow subflow rcv wnd to shrink

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: mptcp: allow subflow rcv wnd to shrink In MPTCP connection, the `window` field in the TCP header refers to the MPTCP-level rcv_nxt and it's right edge should not move backward. Such constraint is enforced at DSS option generation time. At the same time, the TCP stack ensures independently that the TCP-level rcv wnd right's edge does not move backward. That in turn causes artificial inflating of the MPTCP rcv window when the incoming data is acked at the TCP level and is OoO in the MPTCP sequence space (or lands in the backlog). As a consequence, the incoming traffic can exceed the receiver rcvbuf size even when the sender is not misbehaving. Prevent such scenario forcibly allowing the TCP subflow to shrink the TCP-level rcv wnd regardless of the current netns setting.

Products: Kernel
Affected versions: Not specified
Fixed versions: 6.1.176, 6.12.94, 6.18.36, 6.6.143, 7.0.13
CVEs: CVE-2026-53183
Confirmed fixed CVEs: Not specified
Updated in this feed: 2 Nov 2026, 18:16 UTC · Revision 1

Source evidence

mptcp: allow subflow rcv wnd to shrink

core-osv · Original source

Published 25 Jun 2026, 08:38 UTC

osv:CVE-2026-53183

Kernel

Fixed versions: 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13

Complete source record

{
  "id": "ef27ba43ebdd9612043db85231664fe4459eff75ff654bd57a4a2c23dbbe66ce",
  "url": "https://osv.dev/vulnerability/CVE-2026-53183",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mptcp: allow subflow rcv wnd to shrink",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mptcp: allow subflow rcv wnd to shrink In MPTCP connection, the `window` field in the TCP header refers to the MPTCP-level rcv_nxt and it's right edge should not move backward. Such constraint is enforced at DSS option generation time. At the same time, the TCP stack ensures independently that the TCP-level rcv wnd right's edge does not move backward. That in turn causes artificial inflating of the MPTCP rcv window when the incoming data is acked at the TCP level and is OoO in the MPTCP sequence space (or lands in the backlog). As a consequence, the incoming traffic can exceed the receiver rcvbuf size even when the sender is not misbehaving. Prevent such scenario forcibly allowing the TCP subflow to shrink the TCP-level rcv wnd regardless of the current netns setting.",
    "evidence": "osv:CVE-2026-53183",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.176",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.143",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.94",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.36",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.13",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-53183",
      "aliases": [
        "CVE-2026-53183"
      ],
      "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": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
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                {
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                {
                  "fixed": "653245266913f03fcf21cbca68eed5c197a33e52"
                },
                {
                  "fixed": "c297a4e65c50a2b807d9309b22615080faffa8f3"
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                {
                  "fixed": "da23be77e1292cd611e736c3aa17da633d7ddce7"
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              ]
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          ],
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            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53183.json"
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          "ranges": [
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              "type": "ECOSYSTEM",
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              ]
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            {
              "type": "ECOSYSTEM",
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                {
                  "introduced": "6.7.0"
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                {
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            {
              "type": "ECOSYSTEM",
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                  "introduced": "6.13.0"
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            {
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                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.13"
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              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53183.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:21.800176900Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-784472.html",
        "https://git.kernel.org/stable/c/653245266913f03fcf21cbca68eed5c197a33e52",
        "https://git.kernel.org/stable/c/aa3861f40ac32706d9e97bfac76984613e278788",
        "https://git.kernel.org/stable/c/b1fd13074f22105deec45aa02283e322733e0c2d",
        "https://git.kernel.org/stable/c/bf364b0f10b27679140699821f88af7f01e2a6e3",
        "https://git.kernel.org/stable/c/c297a4e65c50a2b807d9309b22615080faffa8f3",
        "https://git.kernel.org/stable/c/da23be77e1292cd611e736c3aa17da633d7ddce7",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53183.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53183",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53183.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53183",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 488250,
  "published_at": "2026-06-25T08:38:57.443+00:00"
}