{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-97984",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-25T10:18:58.208Z",
        "datePublished": "2026-09-25T10:23:19.568Z",
        "dateUpdated": "2026-10-19T09:11:51.310Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-19T09:11:51.310Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: Fix UDP length overflow with PMTU discover and big MTU\n\nThis commit bounds cork->base.fragsize to IP6_MAX_MTU for UDP sockets to\navoid a possible overflow of UDP length that triggers a WARN in\nudp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to\nIPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over\na netdev with an unusually large MTU.\n\nSteps to reproduce (included in the new selftest):\n\n1. Set device MTU bigger than IP6_MAX_MTU. cork->base.fragsize will be\n   set to that MTU in ip6_setup_cork.\n2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It\n   lets maxnonfragsize be set to device MTU (cork->fragsize) in\n   __ip6_append_data, rather than to IP6_MAX_MTU.\n3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of\n   IPv6 header). Device MTU allows it (it's only one byte bigger than\n   IP6_MAX_MTU, and the device MTU is bigger than that).\n4. The UDP length in the built packet is 65536, which overflows the\n   16-bit length field and triggers the WARN in udp_set_len_short.\n\nTo avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit\nthe change to UDP sockets only.\n\nThe original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to\npredate git history (verified reproduction on 2.6.21), was fixed later,\nand then reappeared in commit 427faee167bc (\"net: ipv6: introduce\nip6_dst_mtu_maybe_forward\"), which is chosen as the Fixes tag here. The\noverflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in\ncommit 628a5c561890 (\"[INET]: Add IP(V6)_PMTUDISC_RPOBE\")."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ipv6/ip6_output.c"
                    ],
                    "versions": [
                        {
                            "version": "427faee167bce4ccb0b22f6815a9ac509e31d4c3",
                            "lessThan": "1dd562f3019019ffdf4b396570613053facda9ee",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "427faee167bce4ccb0b22f6815a9ac509e31d4c3",
                            "lessThan": "1d56a00ec91f2885c64ea5b8cea18cb746b91bbb",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "427faee167bce4ccb0b22f6815a9ac509e31d4c3",
                            "lessThan": "ce66352d3eb21825410af8b91db7cc4bb8e22c98",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "427faee167bce4ccb0b22f6815a9ac509e31d4c3",
                            "lessThan": "e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "427faee167bce4ccb0b22f6815a9ac509e31d4c3",
                            "lessThan": "0ae10b6be49b425827659b23bcce498f80eb7182",
                            "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/ipv6/ip6_output.c"
                    ],
                    "versions": [
                        {
                            "version": "5.15",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "5.15",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.158",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.111",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.53",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.7",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "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": "5.15",
                                    "versionEndExcluding": "6.6.158"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                                    "versionStartIncluding": "5.15",
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                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                                },
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                                    "versionStartIncluding": "5.15",
                                    "versionEndExcluding": "7.3"
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                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/1dd562f3019019ffdf4b396570613053facda9ee"
                },
                {
                    "url": "https://git.kernel.org/stable/c/1d56a00ec91f2885c64ea5b8cea18cb746b91bbb"
                },
                {
                    "url": "https://git.kernel.org/stable/c/ce66352d3eb21825410af8b91db7cc4bb8e22c98"
                },
                {
                    "url": "https://git.kernel.org/stable/c/e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc"
                },
                {
                    "url": "https://git.kernel.org/stable/c/0ae10b6be49b425827659b23bcce498f80eb7182"
                }
            ],
            "title": "net: ipv6: Fix UDP length overflow with PMTU discover and big MTU",
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    }
}