{"cve":"CVE-2026-99055","nvd":{"published":"2026-10-23T13:17:29.140","modified":"2026-10-23T13:17:29.140","status":"Received","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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/1c7463ac0e99cc91c4eecc1b69a740ef1a619932","https://git.kernel.org/stable/c/3aa6f536a95eb0617c313ae2eb76fdfa85331f85","https://git.kernel.org/stable/c/563d3564513496b9ce3b3ba7a5154427554d0f06","https://git.kernel.org/stable/c/8b1f0af1fd5fd113432233ed8a3862ee7c30a84f"],"products":[],"source":"nvd","synced_at":"2026-10-23T16:39:28.036610720+00:00"},"epss":{"cve":"CVE-2026-99055","score":0.00168,"percentile":0.0611,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}