{"cve":"CVE-2026-99039","nvd":{"published":"2026-10-23T13:17:27.223","modified":"2026-10-23T13:17:27.223","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmemstick: core: wait for request completion before freeing card\n\nIn memstick_alloc_card() and memstick_set_rw_addr(),\nwait_for_completion_timeout() is used to wait for device identification\nand address configuration requests to complete.\n\nThe memstick subsystem does not provide an abort or cancellation\ncallback in struct memstick_host for in-flight requests. If\nwait_for_completion_timeout() expires (for instance, when a USB transfer\nor command retry is delayed), memstick_alloc_card() returns an error and\nfrees the memstick_dev structure via kfree(card).\n\nHowever, the host controller driver (such as rtsx_usb_ms) is still\nrunning the request asynchronously in worker context. When the transfer\neventually finishes, the driver writes into host->req->data, which\npoints to memory inside the already freed card structure. This leads to\na KASAN slab-use-after-free write:\n\n  BUG: KASAN: slab-use-after-free in ms_read_bytes+0x8fe/0x990\n  Write of size 1 at addr ffff88813c188079 by task kworker/1:5/5239\n  Workqueue: events rtsx_usb_ms_handle_req\n  Call Trace:\n   ms_read_bytes+0x8fe/0x990 drivers/memstick/host/rtsx_usb_ms.c:450\n   rtsx_usb_ms_issue_cmd drivers/memstick/host/rtsx_usb_ms.c:477 [inline]\n   rtsx_usb_ms_handle_req+0x557/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:531\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n   worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560\n   kthread+0x373/0x450 kernel/kthread.c:436\n\n  Allocated by task 1662:\n   memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline]\n   memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n\n  Freed by task 1662:\n   kfree+0x20c/0x650 mm/slub.c:6792\n   memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline]\n   memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n\nHost controller drivers (rtsx_usb_ms, jmb38x_ms, tifm_ms, r592) already\nimplement their own hardware and bus timeouts, and callers in\nmspro_block and ms_block already rely on wait_for_completion()\nunconditionally.\n\nReplace wait_for_completion_timeout() with wait_for_completion() in\nmemstick_set_rw_addr() and memstick_alloc_card() so that the card\nstructure is never freed while an asynchronous request is in flight.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/3af81770e2011c6ac7bb597a4af2e4f3591f928c","https://git.kernel.org/stable/c/810580cf60edc75c9891c2de3225e4cda78e4d9f","https://git.kernel.org/stable/c/aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582","https://git.kernel.org/stable/c/c3ab92542475d59ae685cbb294e70ca4d0ba38e9","https://git.kernel.org/stable/c/f2795c50144d528dabc2cf2fd53c0f0c63a823a1"],"products":[],"source":"nvd","synced_at":"2026-10-23T16:39:28.036610720+00:00"},"epss":{"cve":"CVE-2026-99039","score":0.00168,"percentile":0.06163,"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."]}