{"id":"CVE-2026-89549","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89549","summary":"sunrpc: route to a populated pool in svc_pool_for_cpu()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: route to a populated pool in svc_pool_for_cpu()\n\nsvc_set_num_threads() spreads the requested threads evenly across the\nservice's pools (base = nrservs / sv_nrpools).  When a service runs\nfewer threads than it has pools -- e.g. an nfsd configured with fewer\nthreads than the host has NUMA nodes while running in \"pernode\" or\n\"percpu\" mode -- the trailing pools are left with no threads at all.\n\nsvc_xprt_enqueue() selects a pool from the CPU servicing the transport,\nqueues the transport on that pool's sp_xprts, and only wakes a thread\nfrom the same pool.  Each thread services exclusively its own pool, so a\ntransport that lands on a threadless pool is enqueued on sp_xprts and\nnever picked up: the connection hangs indefinitely.\n\nHave svc_pool_for_cpu() skip pools that currently have no threads,\nfalling back to the next populated pool.  This trades NUMA locality for\na guarantee that the work is actually serviced.  sp_nrthreads is only\nupdated under the service mutex; the lockless read here is a best-effort\nrouting hint, so annotate it with data_race().","published":"2026-09-11T19:44:23.928Z","modified":"2026-09-14T03:46:12.938524918Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/011479cf9a7657d4a3e7cc42a784ac63df594170"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f766d2d0b4dabf54f8b35812df2b4f481d13316"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9d04d64ad192439835ed9884d767353061c3ed6f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f6310491c4cdb88af73aa551ec9df1f10a90c709"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89549.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89549"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:12.938524918Z"}}