{"id":"CVE-2026-80789","title":"nvmet-tcp: bound SGL data length before allocating command buffers","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: bound SGL data length before allocating command buffers\n\nnvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length\nand, for the in-capsule offset des…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < f63e89a0310264264923f84406dea05fe752de62","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 0952541b153e258b99d39cdb03ea6919fdeb41d0","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < d2acc96c528d589f5827cfb90e8e9229dd9d8cb4","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 6d27199ebe8cb223022150f74be13f154a964474","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 14dbe37681a6a7e346fc147bb363ec7cca3180a0","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < d895e66628f939edbb98608f6e033d3d39e6e546","Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 4a3f00262a044e8e15064b1a6860968bf0500bf4","Linux 5.0"],"published":"2026-09-04","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:43:42.439Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80789","references":[{"url":"https://git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5"},{"url":"https://git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62"},{"url":"https://git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0"},{"url":"https://git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22"},{"url":"https://git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4"},{"url":"https://git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474"},{"url":"https://git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0"},{"url":"https://git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546"},{"url":"https://git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4"}],"tags":["cve.org"],"epss":0.00234,"epssPercentile":0.13287,"ingestedAt":"2026-10-19T10:20:54.958Z","slug":"CVE-2026-80789","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: bound SGL data length before allocating command buffers\n\nnvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length\nand, for the in-capsule offset descriptor (type 0x01), checks it\nagainst port->inline_data_size before use. Any other SGL descriptor\ntype -- including the non-inline transport SGL data-block descriptor\n(type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A,\nthe type a real host uses for out-of-capsule writes) skips that check\nentirely and falls straight through to:\n\n\tcmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt);\n\nwith len taken directly from the wire, unbounded up to 4 GiB.\n\nnvmet_req_init() only parses the command and never inspects\nsgl->length, and nvmet_check_transfer_len() -- the only other place\ntransfer_len is validated -- runs later, from req->execute(), after\nthe allocation has already happened. For a write command the target\nresponds with an R2T and parks the command waiting for the host to\nsend the data; if the host (or an unauthenticated peer that simply\nnever follows up) never does, the sgl_alloc() buffer stays resident\nfor the life of the command. NVMe/TCP has no mandatory authentication\nin the default configuration, so any peer able to reach the target\nportal and complete a Fabrics connect can drive this with a single\ncrafted command, repeatable across queues and connections for\namplification. This is unbounded kernel memory allocation\ntriggered by a remote, effectively unauthenticated peer.\n\nValidate len against the same NVMET_TCP_MAXH2CDATA ceiling this file\nalready uses to bound per-PDU H2C data, for every SGL descriptor type,\nbefore doing any allocation. This closes the gap for the non-inline\ndescriptor while leaving the existing, tighter inline_data_size check\nin place for the in-capsule case.\n\nRuntime-verified on a v6.19 KASAN stand: with this bound in place, a\ncrafted write command carrying an oversized non-inline SGL length is\nrejected before sgl_alloc() runs, where the same request previously\ndrove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that\nstayed resident pending an R2T the host never satisfies.\n\n## Affected\n\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < f63e89a0310264264923f84406dea05fe752de62`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 0952541b153e258b99d39cdb03ea6919fdeb41d0`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < d2acc96c528d589f5827cfb90e8e9229dd9d8cb4`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 6d27199ebe8cb223022150f74be13f154a964474`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 14dbe37681a6a7e346fc147bb363ec7cca3180a0`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < d895e66628f939edbb98608f6e033d3d39e6e546`\n- `Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 4a3f00262a044e8e15064b1a6860968bf0500bf4`\n- `Linux 5.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}