{"id":"CVE-2026-89546","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89546","summary":"SUNRPC: close backchannel before destroying callback service","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: close backchannel before destroying callback service\n\nA backchannel receive can complete a request while the NFS callback\nservice is being torn down.  xprt_complete_bc_request() removes the\nrequest from bc_pa_list, drops bc_alloc_count, marks the request in use,\nand then asks xprt_enqueue_bc_request() to hand it to the callback\nservice.\n\nIf teardown has already cleared xprt->bc_serv, xprt_enqueue_bc_request()\ncurrently returns without enqueueing or freeing the committed request.\nThe xprt_get() taken on entry is leaked as well.  If the producer wins\nthe race before bc_serv is cleared, it can also enqueue onto sv_cb_list\nafter nfs_callback_down() has stopped the callback threads, leaving the\nrequest linked to a svc_serv that is about to be freed.\n\nClose the producer side before callback threads are stopped.  Add\nxprt_svc_shutdown_bc() to clear xprt->bc_serv under bc_pa_lock, and call\nit on callback shutdown and callback-start failure before stopping the\nservice threads.  Requests that lose the NULL transition in\nxprt_enqueue_bc_request() are released through the normal backchannel\nfree path after balancing bc_slot_count.  Finally, drain any remaining\nsv_cb_list requests after the callback threads have stopped and before\nsvc_destroy() frees the service.","published":"2026-09-11T19:44:21.898Z","modified":"2026-09-14T03:46:12.889704480Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"7.2.4"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3674f780f47d2906b5a0f7199b66973067bdfeca"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6debde9e3e6ae21dcca75837b4247b13ca4ea2b8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89546.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89546"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:12.889704480Z"}}