{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-52940",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-06-09T07:44:35.370Z",
        "datePublished": "2026-06-24T07:14:29.281Z",
        "dateUpdated": "2026-06-24T07:14:29.281Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-06-24T07:14:29.281Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntun: zero the whole vnet header in tun_put_user()\n\ntun_put_user() declares an on-stack struct virtio_net_hdr_v1_hash_tunnel\nwithout zeroing it. For a non-tunnel skb, virtio_net_hdr_tnl_from_skb()\nonly initializes the first 10 bytes (sizeof(struct virtio_net_hdr)),\nleaving bytes 10..23 (num_buffers and the hash/tunnel fields) as stack\ngarbage.\n\nAn unprivileged user can set the vnet header size to 24 with\nTUNSETVNETHDRSZ, so __tun_vnet_hdr_put() copies all 24 bytes of the\npartially-initialized struct to userspace, leaking 14 bytes of kernel\nstack on every read of a non-tunnel packet.\n\nFix it the same way tun_get_user() already does by zeroing the whole\nheader right after declaration."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/net/tun.c"
                    ],
                    "versions": [
                        {
                            "version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37",
                            "lessThan": "5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37",
                            "lessThan": "585cb85e9a29185be05f326369573c2663cf4380",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "288f30435132d2f9e7a29ec9b9745a4f9dc7fd37",
                            "lessThan": "7f2fcff15e99bb852f6967396ed12b38376e2c8d",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/net/tun.c"
                    ],
                    "versions": [
                        {
                            "version": "6.17",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.17",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.36",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0.13",
                            "lessThanOrEqual": "7.0.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1",
                            "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": "6.17",
                                    "versionEndExcluding": "6.18.36"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.17",
                                    "versionEndExcluding": "7.0.13"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.17",
                                    "versionEndExcluding": "7.1"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/5fd1fa5a4254bfdd70571c77f5e3bcb4e43738d5"
                },
                {
                    "url": "https://git.kernel.org/stable/c/585cb85e9a29185be05f326369573c2663cf4380"
                },
                {
                    "url": "https://git.kernel.org/stable/c/7f2fcff15e99bb852f6967396ed12b38376e2c8d"
                }
            ],
            "title": "tun: zero the whole vnet header in tun_put_user()",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}