{"id":"CVE-2026-99055","state":"PUBLISHED","title":"tcp: reject net_iov in zerocopy receive mapping hints","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: reject net_iov in zerocopy receive mapping hints\n\nAfter copying a readable prefix, receive_fallback_to_copy() asks\ntcp_zerocopy_set_hint_for_skb() where page mapping can resume. If the\nnext skb is unreadable, find_next_mappable_frag() passes its net_iov\nfragment to can_map_frag().\n\nskb_frag_page() returns NULL for a net_iov, but can_map_frag()\ndereferences it in PageCompound(). A v7.2 KASAN run on a connected TCP\nsocket with 64 readable bytes followed by a 4096-byte NET_IOV_DMABUF\nfragment reported:\n\n  BUG: KASAN: null-ptr-deref in can_map_frag\n  tcp_zerocopy_receive -> can_map_frag\n  Kernel panic - not syncing: KASAN: panic_on_warn set\n\nThe diagnostic inserted the net_iov directly because the test host has\nno devmem-capable NIC. Hardware end-to-end reachability remains untested\nand requires CONFIG_NET_DEVMEM plus a supported DMA-buf-bound RX queue.\n\nReject all net_iov fragments before skb_frag_page(). This covers both\nDMABUF and IOURING net_iov types while leaving page-backed checks\nunchanged. With the guard, the same queue copied the readable prefix,\nreturned a 4096-byte skip hint, and completed without a fault.","publishedAt":"2026-10-23T12:22:39.451Z","updatedAt":"2026-10-23T12:22:39.451Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"563d3564513496b9ce3b3ba7a5154427554d0f06","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"1c7463ac0e99cc91c4eecc1b69a740ef1a619932","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"3aa6f536a95eb0617c313ae2eb76fdfa85331f85","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"8b1f0af1fd5fd113432233ed8a3862ee7c30a84f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp.c"]}],"references":["https://git.kernel.org/stable/c/563d3564513496b9ce3b3ba7a5154427554d0f06","https://git.kernel.org/stable/c/1c7463ac0e99cc91c4eecc1b69a740ef1a619932","https://git.kernel.org/stable/c/3aa6f536a95eb0617c313ae2eb76fdfa85331f85","https://git.kernel.org/stable/c/8b1f0af1fd5fd113432233ed8a3862ee7c30a84f"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99055.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99055","state":"PUBLISHED","datePublished":"2026-10-23T12:22:39.451Z","dateUpdated":"2026-10-23T12:22:39.451Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.388Z"},"containers":{"cna":{"title":"tcp: reject net_iov in zerocopy receive mapping hints","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: reject net_iov in zerocopy receive mapping hints\n\nAfter copying a readable prefix, receive_fallback_to_copy() asks\ntcp_zerocopy_set_hint_for_skb() where page mapping can resume. If the\nnext skb is unreadable, find_next_mappable_frag() passes its net_iov\nfragment to can_map_frag().\n\nskb_frag_page() returns NULL for a net_iov, but can_map_frag()\ndereferences it in PageCompound(). A v7.2 KASAN run on a connected TCP\nsocket with 64 readable bytes followed by a 4096-byte NET_IOV_DMABUF\nfragment reported:\n\n  BUG: KASAN: null-ptr-deref in can_map_frag\n  tcp_zerocopy_receive -> can_map_frag\n  Kernel panic - not syncing: KASAN: panic_on_warn set\n\nThe diagnostic inserted the net_iov directly because the test host has\nno devmem-capable NIC. Hardware end-to-end reachability remains untested\nand requires CONFIG_NET_DEVMEM plus a supported DMA-buf-bound RX queue.\n\nReject all net_iov fragments before skb_frag_page(). This covers both\nDMABUF and IOURING net_iov types while leaving page-backed checks\nunchanged. With the guard, the same queue copied the readable prefix,\nreturned a 4096-byte skip hint, and completed without a fault."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"563d3564513496b9ce3b3ba7a5154427554d0f06","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"1c7463ac0e99cc91c4eecc1b69a740ef1a619932","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"3aa6f536a95eb0617c313ae2eb76fdfa85331f85","versionType":"git"},{"version":"9f6b619edf2e85746f261b42ae8f818a59d126f7","status":"affected","lessThan":"8b1f0af1fd5fd113432233ed8a3862ee7c30a84f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/563d3564513496b9ce3b3ba7a5154427554d0f06"},{"url":"https://git.kernel.org/stable/c/1c7463ac0e99cc91c4eecc1b69a740ef1a619932"},{"url":"https://git.kernel.org/stable/c/3aa6f536a95eb0617c313ae2eb76fdfa85331f85"},{"url":"https://git.kernel.org/stable/c/8b1f0af1fd5fd113432233ed8a3862ee7c30a84f"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-23T12:22:39.451Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.113"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.2.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}