{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-80585",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-08-26T14:34:25.769Z",
        "datePublished": "2026-08-26T14:37:40.901Z",
        "dateUpdated": "2026-08-26T14:37:40.901Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-26T14:37:40.901Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fastopen: only mark MPTFO subflows with SYN data\n\nPassive TCP Fast Open accepts a valid-cookie SYN even when it carries\nno data. In that case the child socket's receive queue is intentionally\nleft empty.\n\nmptcp_fastopen_subflow_synack_set_params() set is_mptfo before checking\nfor queued SYN data. That made data-less TFO SYNs hit a WARN and, if\nthe warning was non-fatal, left stale MPTFO state behind. The stale\nflag could later trigger a state-confusion bug in\ncheck_fully_established().\n\nOnly mark the subflow as MPTFO after confirming that an SKB was queued.\nReturn quietly when the receive queue is empty.\n\nNote that mptcp_subflow_context's is_mptfo field is now not just about\nsubflows where the TFO was present, but about MPTFO subflow that\nconsumed SYN data. Only having a valid cookie but not carrying data is\nnot really \"doing TFO\"."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/mptcp/fastopen.c"
                    ],
                    "versions": [
                        {
                            "version": "36b122baf6a8bd46b4a591f12f4ed17b22257408",
                            "lessThan": "f75f174edc865738522e514d042cf5627f084859",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "36b122baf6a8bd46b4a591f12f4ed17b22257408",
                            "lessThan": "fca7e444c04689fe4cc6b56f2725f804a4bb1ef9",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "36b122baf6a8bd46b4a591f12f4ed17b22257408",
                            "lessThan": "75e564b2ced1cc3d9a8904c7d2d2bb448fffb8b5",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "36b122baf6a8bd46b4a591f12f4ed17b22257408",
                            "lessThan": "72b4a0c51a4b550d40301d60a366b429b8c8e78d",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "36b122baf6a8bd46b4a591f12f4ed17b22257408",
                            "lessThan": "e00b63056fb4f261455b3e5df5268a1f8ce47a87",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/mptcp/fastopen.c"
                    ],
                    "versions": [
                        {
                            "version": "6.2",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.2",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.153",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.105",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.46",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1.10",
                            "lessThanOrEqual": "7.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.2",
                                    "versionEndExcluding": "6.6.153"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.2",
                                    "versionEndExcluding": "6.12.105"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.2",
                                    "versionEndExcluding": "6.18.46"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.2",
                                    "versionEndExcluding": "7.1.10"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.2",
                                    "versionEndExcluding": "7.2"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/f75f174edc865738522e514d042cf5627f084859"
                },
                {
                    "url": "https://git.kernel.org/stable/c/fca7e444c04689fe4cc6b56f2725f804a4bb1ef9"
                },
                {
                    "url": "https://git.kernel.org/stable/c/75e564b2ced1cc3d9a8904c7d2d2bb448fffb8b5"
                },
                {
                    "url": "https://git.kernel.org/stable/c/72b4a0c51a4b550d40301d60a366b429b8c8e78d"
                },
                {
                    "url": "https://git.kernel.org/stable/c/e00b63056fb4f261455b3e5df5268a1f8ce47a87"
                }
            ],
            "title": "mptcp: fastopen: only mark MPTFO subflows with SYN data",
            "x_generator": {
                "engine": "bippy-1.2.0"
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    }
}