{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "bf9f1baa279f0758dc2297080360c5a616843927"
            },
            {
              "fixed": "128b03ccb2582a643983a48a37fda58df80edbde"
            },
            {
              "fixed": "60313768a8edc7094435975587c00c2d7b834083"
            },
            {
              "fixed": "2d64618ea846d8d033477311f805ca487d6a6696"
            },
            {
              "fixed": "474e00b935db250cac320d10c1d3cf4e44b46721"
            },
            {
              "fixed": "0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.3.0"
            },
            {
              "fixed": "6.6.136"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.82"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.23"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31429.json"
  },
  "details": "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() -\u003e 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.",
  "id": "CVE-2026-31429",
  "modified": "2026-07-15T01:49:20.587846531Z",
  "published": "2026-04-20T09:43:03.194Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0f42e3f4fe2a58394e37241d02d9ca6ab7b7d516"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/128b03ccb2582a643983a48a37fda58df80edbde"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2d64618ea846d8d033477311f805ca487d6a6696"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/474e00b935db250cac320d10c1d3cf4e44b46721"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/60313768a8edc7094435975587c00c2d7b834083"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31429.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31429"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "summary": "net: skb: fix cross-cache free of KFENCE-allocated skb head"
}