{"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"}}}}