{"id":"CVE-2026-81009","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/query: cap user size passed to copy_struct_to_user\n\nio_handle_query_entry() clamps hdr.size for the inbound copy_from_user()\nbut keeps the original user value …","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/query: cap user size passed to copy_struct_to_user\n\nio_handle_query_entry() clamps hdr.size for the inbound copy_from_user()\nbut keeps the original user value …","severity":"medium","vendor":"Linux","product":"Linux","affected":["Linux >= c265ae75f900cea4e415230a77b5d152377627dd < 417e02f7b6051765b91cf1289071882eebd172e0","Linux >= c265ae75f900cea4e415230a77b5d152377627dd < 2b8ad4981ecedb14c1fdd811ab977010b23933e6","Linux >= c265ae75f900cea4e415230a77b5d152377627dd < ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b","Linux 6.18"],"published":"2026-09-11","updated":"2026-09-11","sourceUpdated":"2026-09-11T20:19:09.687","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81009","references":[{"url":"https://git.kernel.org/stable/c/2b8ad4981ecedb14c1fdd811ab977010b23933e6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/417e02f7b6051765b91cf1289071882eebd172e0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-81009.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-81009"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532289"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-81009"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81009"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-81009.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ingestedAt":"2026-09-14T05:48:34.517Z","epss":0.00206,"epssPercentile":0.0945,"cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-770"],"slug":"CVE-2026-81009","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/query: cap user size passed to copy_struct_to_user\n\nio_handle_query_entry() clamps hdr.size for the inbound copy_from_user()\nbut keeps the original user value as usize. copy_struct_to_user() uses\nthat usize and, when it is larger than the kernel result, clear_user()s\nthe trailing bytes.\n\nAs hdr.size is a __u32, a query can request nearly 4 GiB of zeroing,\nincluding on the error path where res_size stays 0. The interface is\nreachable without a ring via IORING_REGISTER_QUERY.\n\nReject sizes larger than PAGE_SIZE, as recommended for copy_struct_*\ninterfaces.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-81009.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":204136,"id":"CVE-2026-81009","ts":1789490232003,"field":"cvss","old":null,"new":"5.5"},{"seq":204135,"id":"CVE-2026-81009","ts":1789490232003,"field":"severity","old":"none","new":"medium"},{"seq":147432,"id":"CVE-2026-81009","ts":1789270210886,"field":"cvss","old":null,"new":"4.7"},{"seq":147431,"id":"CVE-2026-81009","ts":1789270210886,"field":"severity","old":"none","new":"medium"},{"seq":109184,"id":"CVE-2026-81009","ts":1789183730639,"field":"cvss","old":null,"new":"4.7"},{"seq":109183,"id":"CVE-2026-81009","ts":1789183730639,"field":"severity","old":"none","new":"medium"}]}