{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-63836",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-07-19T07:54:57.015Z",
        "datePublished": "2026-07-19T12:02:27.166Z",
        "dateUpdated": "2026-08-17T04:51:47.476Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-17T04:51:47.476Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: tp_meter: avoid divide-by-zero for dec_cwnd\n\nThe cwnd is always MSS <= cwnd <= 0x20000000. But the calculation in\nbatadv_tp_update_cwnd() assumes unsigned 32 bit arithmetics.\n\n    ((mss * 8) ** 2) / (cwnd * 8)\n\nIn case cwnd is actually 0x20000000, it will be shifted by 3 bit to the\nleft end up at 0x100000000 or U32_MAX + 1. It will therefore wrap around\nand be 0 - resulting in:\n\n    ((mss * 8) ** 2) / 0\n\nThis is of course invalid and cannot be calculated. The calculation should\nmust be simplified to avoid this overflow:\n\n   (mss ** 2) * 8 / cwnd\n\nIt will keep the precision enhancement from the scaling (by 8) but avoid\nthe overflow in the divisor.\n\nIn theory, there could still be an overflow in the dividend. It is at the\nmoment fixed to BATADV_TP_PLEN in batadv_tp_recv_ack() - so it is not an\nimminent problem. But allowing it to use the whole u32 bit range, would\nmean that it can still use up to 67 bits. To keep this calculation safe for\n32 bit arithmetic, mss must never use more than floor((32 - 3) / 2) bits -\nor in other words: must never be larger than 16383."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/batman-adv/tp_meter.c"
                    ],
                    "versions": [
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "35264c4d46067d6312871488c810cef387f8c1f6",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "1381b021bf886b793fa5ffb895a8efae7ba0318f",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "d08b69da40a101df1e28bfe1e8fa7a09ffa41107",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "cd74176cf1685f35a2e5f212d15748bbfecb53b6",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "ac229c86e49fdb96d91f51bc2fa37a9c4f58c44f",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "7d2a44bc6bbe39aed03c68864aa0e54e04a50278",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "585616dab0aa9c45bc11b2c8082ca78533bc00e9",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "33a3bb4a3345bb511f9c69c913da95d4693e2a4e",
                            "lessThan": "33ccd52f3cc9ed46ce395199f89aa3234dc83314",
                            "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/batman-adv/tp_meter.c"
                    ],
                    "versions": [
                        {
                            "version": "4.8",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "4.8",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.260",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.211",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.177",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.144",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.95",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.38",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1.3",
                            "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": "4.8",
                                    "versionEndExcluding": "5.10.260"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "5.15.211"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "6.1.177"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "6.6.144"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "6.12.95"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "6.18.38"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "7.1.3"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "4.8",
                                    "versionEndExcluding": "7.2"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/35264c4d46067d6312871488c810cef387f8c1f6"
                },
                {
                    "url": "https://git.kernel.org/stable/c/1381b021bf886b793fa5ffb895a8efae7ba0318f"
                },
                {
                    "url": "https://git.kernel.org/stable/c/d08b69da40a101df1e28bfe1e8fa7a09ffa41107"
                },
                {
                    "url": "https://git.kernel.org/stable/c/cd74176cf1685f35a2e5f212d15748bbfecb53b6"
                },
                {
                    "url": "https://git.kernel.org/stable/c/ac229c86e49fdb96d91f51bc2fa37a9c4f58c44f"
                },
                {
                    "url": "https://git.kernel.org/stable/c/7d2a44bc6bbe39aed03c68864aa0e54e04a50278"
                },
                {
                    "url": "https://git.kernel.org/stable/c/585616dab0aa9c45bc11b2c8082ca78533bc00e9"
                },
                {
                    "url": "https://git.kernel.org/stable/c/33ccd52f3cc9ed46ce395199f89aa3234dc83314"
                }
            ],
            "title": "batman-adv: tp_meter: avoid divide-by-zero for dec_cwnd",
            "x_generator": {
                "engine": "bippy-1.2.0"
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        }
    }
}