{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-31429",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-03-09T15:48:24.089Z",
        "datePublished": "2026-04-20T09:43:03.194Z",
        "dateUpdated": "2026-05-11T22:08:32.321Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-05-11T22:08:32.321Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skb: fix cross-cache free of KFENCE-allocated skb head\n\nSKB_SMALL_HEAD_CACHE_SIZE is intentionally set to a non-power-of-2\nvalue (e.g. 704 on x86_64) to avoid collisions with generic kmalloc\nbucket sizes. This ensures that skb_kfree_head() can reliably use\nskb_end_offset to distinguish skb heads allocated from\nskb_small_head_cache vs. generic kmalloc caches.\n\nHowever, when KFENCE is enabled, kfence_ksize() returns the exact\nrequested allocation size instead of the slab bucket size. If a caller\n(e.g. bpf_test_init) allocates skb head data via kzalloc() and the\nrequested size happens to equal SKB_SMALL_HEAD_CACHE_SIZE, then\nslab_build_skb() -> ksize() returns that exact value. After subtracting\nskb_shared_info overhead, skb_end_offset ends up matching\nSKB_SMALL_HEAD_HEADROOM, causing skb_kfree_head() to incorrectly free\nthe object to skb_small_head_cache instead of back to the original\nkmalloc cache, resulting in a slab cross-cache free:\n\n  kmem_cache_free(skbuff_small_head): Wrong slab cache. Expected\n  skbuff_small_head but got kmalloc-1k\n\nFix this by always calling kfree(head) in skb_kfree_head(). This keeps\nthe free path generic and avoids allocator-specific misclassification\nfor KFENCE objects."
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/core/skbuff.c"
                    ],
                    "versions": [
                        {
                            "version": "bf9f1baa279f0758dc2297080360c5a616843927",
                            "lessThan": "128b03ccb2582a643983a48a37fda58df80edbde",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "bf9f1baa279f0758dc2297080360c5a616843927",
                            "lessThan": "60313768a8edc7094435975587c00c2d7b834083",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "bf9f1baa279f0758dc2297080360c5a616843927",
                            "lessThan": "2d64618ea846d8d033477311f805ca487d6a6696",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "bf9f1baa279f0758dc2297080360c5a616843927",
                            "lessThan": "474e00b935db250cac320d10c1d3cf4e44b46721",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "bf9f1baa279f0758dc2297080360c5a616843927",
                            "lessThan": "0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516",
                            "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/core/skbuff.c"
                    ],
                    "versions": [
                        {
                            "version": "6.3",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.3",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.136",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.82",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.23",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.19.13",
                            "lessThanOrEqual": "6.19.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0",
                            "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": "6.3",
                                    "versionEndExcluding": "6.6.136"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.3",
                                    "versionEndExcluding": "6.12.82"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.3",
                                    "versionEndExcluding": "6.18.23"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.3",
                                    "versionEndExcluding": "6.19.13"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.3",
                                    "versionEndExcluding": "7.0"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/128b03ccb2582a643983a48a37fda58df80edbde"
                },
                {
                    "url": "https://git.kernel.org/stable/c/60313768a8edc7094435975587c00c2d7b834083"
                },
                {
                    "url": "https://git.kernel.org/stable/c/2d64618ea846d8d033477311f805ca487d6a6696"
                },
                {
                    "url": "https://git.kernel.org/stable/c/474e00b935db250cac320d10c1d3cf4e44b46721"
                },
                {
                    "url": "https://git.kernel.org/stable/c/0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516"
                }
            ],
            "title": "net: skb: fix cross-cache free of KFENCE-allocated skb head",
            "x_generator": {
                "engine": "bippy-1.2.0"
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        }
    }
}