CVE-2025-39993 (GCVE-0-2025-39993)

Vulnerability from cvelistv5 – Published: 2025-10-15 07:58 – Updated: 2026-08-05 12:06
VLAI
Title
media: rc: fix races with imon_disconnect()
Summary
In the Linux kernel, the following vulnerability has been resolved: media: rc: fix races with imon_disconnect() Syzbot reports a KASAN issue as below: BUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline] BUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627 Read of size 4 at addr ffff8880256fb000 by task syz-executor314/4465 CPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 __create_pipe include/linux/usb.h:1945 [inline] send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627 vfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991 vfs_write+0x2d7/0xdd0 fs/read_write.c:576 ksys_write+0x127/0x250 fs/read_write.c:631 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The iMON driver improperly releases the usb_device reference in imon_disconnect without coordinating with active users of the device. Specifically, the fields usbdev_intf0 and usbdev_intf1 are not protected by the users counter (ictx->users). During probe, imon_init_intf0 or imon_init_intf1 increments the usb_device reference count depending on the interface. However, during disconnect, usb_put_dev is called unconditionally, regardless of actual usage. As a result, if vfd_write or other operations are still in progress after disconnect, this can lead to a use-after-free of the usb_device pointer. Thread 1 vfd_write Thread 2 imon_disconnect ... if usb_put_dev(ictx->usbdev_intf0) else usb_put_dev(ictx->usbdev_intf1) ... while send_packet if pipe = usb_sndintpipe( ictx->usbdev_intf0) UAF else pipe = usb_sndctrlpipe( ictx->usbdev_intf0, 0) UAF Guard access to usbdev_intf0 and usbdev_intf1 after disconnect by checking ictx->disconnected in all writer paths. Add early return with -ENODEV in send_packet(), vfd_write(), lcd_write() and display_open() if the device is no longer present. Set and read ictx->disconnected under ictx->lock to ensure memory synchronization. Acquire the lock in imon_disconnect() before setting the flag to synchronize with any ongoing operations. Ensure writers exit early and safely after disconnect before the USB core proceeds with cleanup. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-16 16:12 UTC
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6856 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < 9348976003e39754af344949579e824a0a210fc4 (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < b03fac6e2a38331faf8510b480becfa90cea1c9f (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < 71c52b073922d05e79e6de7fc7f5f38f927929a4 (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < 71096a6161a25e84acddb89a9d77f138502d26ab (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < 71da40648741d15b302700b68973fe8b382aef3c (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < fd5d3e6b149ec8cce045d86a2b5e3664d6b32ba5 (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < d9f6ce99624a41c3bcb29a8d7d79b800665229dd (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < 2e7fd93b9cc565b839bc55a6662475718963e156 (git)
Affected: 21677cfc562a27e099719d413287bc8d1d24deb7 , < fa0f61cc1d828178aa921475a9b786e7fbb65ccb (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.35
Unaffected: 0 , < 2.6.35 (semver)
Unaffected: 5.4.301 , ≤ 5.4.* (semver)
Unaffected: 5.10.246 , ≤ 5.10.* (semver)
Unaffected: 5.15.195 , ≤ 5.15.* (semver)
Unaffected: 6.1.156 , ≤ 6.1.* (semver)
Unaffected: 6.6.110 , ≤ 6.6.* (semver)
Unaffected: 6.12.51 , ≤ 6.12.* (semver)
Unaffected: 6.16.11 , ≤ 6.16.* (semver)
Unaffected: 6.17.1 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: rc: fix races with imon_disconnect()\n\nSyzbot reports a KASAN issue as below:\nBUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline]\nBUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nRead of size 4 at addr ffff8880256fb000 by task syz-executor314/4465\n\nCPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014\nCall Trace:\n \u003cTASK\u003e\n__dump_stack lib/dump_stack.c:88 [inline]\ndump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106\nprint_address_description mm/kasan/report.c:317 [inline]\nprint_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433\nkasan_report+0xb1/0x1e0 mm/kasan/report.c:495\n__create_pipe include/linux/usb.h:1945 [inline]\nsend_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nvfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991\nvfs_write+0x2d7/0xdd0 fs/read_write.c:576\nksys_write+0x127/0x250 fs/read_write.c:631\ndo_syscall_x64 arch/x86/entry/common.c:50 [inline]\ndo_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80\nentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThe iMON driver improperly releases the usb_device reference in\nimon_disconnect without coordinating with active users of the\ndevice.\n\nSpecifically, the fields usbdev_intf0 and usbdev_intf1 are not\nprotected by the users counter (ictx-\u003eusers). During probe,\nimon_init_intf0 or imon_init_intf1 increments the usb_device\nreference count depending on the interface. However, during\ndisconnect, usb_put_dev is called unconditionally, regardless of\nactual usage.\n\nAs a result, if vfd_write or other operations are still in\nprogress after disconnect, this can lead to a use-after-free of\nthe usb_device pointer.\n\nThread 1 vfd_write                      Thread 2 imon_disconnect\n                                        ...\n                                        if\n                                          usb_put_dev(ictx-\u003eusbdev_intf0)\n                                        else\n                                          usb_put_dev(ictx-\u003eusbdev_intf1)\n...\nwhile\n  send_packet\n    if\n      pipe = usb_sndintpipe(\n        ictx-\u003eusbdev_intf0) UAF\n    else\n      pipe = usb_sndctrlpipe(\n        ictx-\u003eusbdev_intf0, 0) UAF\n\nGuard access to usbdev_intf0 and usbdev_intf1 after disconnect by\nchecking ictx-\u003edisconnected in all writer paths. Add early return\nwith -ENODEV in send_packet(), vfd_write(), lcd_write() and\ndisplay_open() if the device is no longer present.\n\nSet and read ictx-\u003edisconnected under ictx-\u003elock to ensure memory\nsynchronization. Acquire the lock in imon_disconnect() before setting\nthe flag to synchronize with any ongoing operations.\n\nEnsure writers exit early and safely after disconnect before the USB\ncore proceeds with cleanup.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."
        }
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            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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            {
              "lang": "en",
              "value": "AV:L - The vulnerable code is reached through an ordinary `write(2)` syscall on the `/dev/lcd0` character device (`vfd_write`/`lcd_write` \u2192 `send_packet`), i.e. a local attack surface reached via a device file, with no network exposure. The disconnect that frees the `usb_device` is a triggering condition the attacker supplies (their own removable/emulated iMON device or an unplug event), not the attack interface itself.\nAC:L - The attacker controls both sides of the race: they drive an unbounded loop of `write()` calls that hold `ictx-\u003elock` for seconds at a time (`send_packet` waits up to 10 s per packet, six packets per write) while triggering device removal, giving an extremely wide and repeatable window. Syzkaller reproduces it, and failed attempts are harmless, so it can be retried until it lands.\nPR:L - No capability, `CAP_SYS_ADMIN`, or other privilege check exists anywhere on the path \u2014 `display_open()` only checks `display_supported`/`display_isopen`, and `vfd_write`/`lcd_write` go straight to `send_packet()`. Any unprivileged process able to open the display node (routinely group-accessible on media/HTPC systems, and the node the LIRC/LCDproc userspace stack writes to) can trigger it.\nUI:N - The attacker\u0027s own process performs the writes, and the disconnect side is produced by the attacker\u0027s device or unplug action rather than by a victim. No action by another user is needed at any point.\nS:U - The use-after-free corrupts kernel memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed `struct usb_device` is read via `__create_pipe()` (`dev-\u003edevnum`) and then throughout `usb_submit_urb()` (`dev-\u003estate`, `dev-\u003eep_out[]`, `dev-\u003ebus`), so an attacker who reclaims the slab object can read back kernel data and pointers, and the UAF is a general primitive for arbitrary memory disclosure.\nI:H - The stale pointer is stored into the URB and submitted, causing `usb_get_dev(urb-\u003edev)` to write (atomic increment) into freed memory and `bus_to_hcd(urb-\u003edev-\u003ebus)-\u003edriver-\u003eurb_enqueue()` to make an indirect call through a chain rooted in attacker-reclaimable memory \u2014 a control-flow hijack and arbitrary-write primitive.\nA:H - Even without heap grooming, dereferencing and submitting an URB against a freed `usb_device` reliably produces a KASAN splat, oops, or panic, as shown in the syzbot report, and the attacker can repeat it at will."
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                ],
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          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: rc: fix races with imon_disconnect()\n\nSyzbot reports a KASAN issue as below:\nBUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline]\nBUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nRead of size 4 at addr ffff8880256fb000 by task syz-executor314/4465\n\nCPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014\nCall Trace:\n \u003cTASK\u003e\n__dump_stack lib/dump_stack.c:88 [inline]\ndump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106\nprint_address_description mm/kasan/report.c:317 [inline]\nprint_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433\nkasan_report+0xb1/0x1e0 mm/kasan/report.c:495\n__create_pipe include/linux/usb.h:1945 [inline]\nsend_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nvfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991\nvfs_write+0x2d7/0xdd0 fs/read_write.c:576\nksys_write+0x127/0x250 fs/read_write.c:631\ndo_syscall_x64 arch/x86/entry/common.c:50 [inline]\ndo_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80\nentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThe iMON driver improperly releases the usb_device reference in\nimon_disconnect without coordinating with active users of the\ndevice.\n\nSpecifically, the fields usbdev_intf0 and usbdev_intf1 are not\nprotected by the users counter (ictx-\u003eusers). During probe,\nimon_init_intf0 or imon_init_intf1 increments the usb_device\nreference count depending on the interface. However, during\ndisconnect, usb_put_dev is called unconditionally, regardless of\nactual usage.\n\nAs a result, if vfd_write or other operations are still in\nprogress after disconnect, this can lead to a use-after-free of\nthe usb_device pointer.\n\nThread 1 vfd_write                      Thread 2 imon_disconnect\n                                        ...\n                                        if\n                                          usb_put_dev(ictx-\u003eusbdev_intf0)\n                                        else\n                                          usb_put_dev(ictx-\u003eusbdev_intf1)\n...\nwhile\n  send_packet\n    if\n      pipe = usb_sndintpipe(\n        ictx-\u003eusbdev_intf0) UAF\n    else\n      pipe = usb_sndctrlpipe(\n        ictx-\u003eusbdev_intf0, 0) UAF\n\nGuard access to usbdev_intf0 and usbdev_intf1 after disconnect by\nchecking ictx-\u003edisconnected in all writer paths. Add early return\nwith -ENODEV in send_packet(), vfd_write(), lcd_write() and\ndisplay_open() if the device is no longer present.\n\nSet and read ictx-\u003edisconnected under ictx-\u003elock to ensure memory\nsynchronization. Acquire the lock in imon_disconnect() before setting\nthe flag to synchronize with any ongoing operations.\n\nEnsure writers exit early and safely after disconnect before the USB\ncore proceeds with cleanup.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmedia: rc: corregir condiciones de carrera con imon_disconnect()\n\nSyzbot informa un problema de KASAN como se detalla a continuaci\u00f3n:\nERROR: KASAN: uso despu\u00e9s de liberaci\u00f3n en __create_pipe include/linux/usb.h:1945 [en l\u00ednea]\nERROR: KASAN: uso despu\u00e9s de liberaci\u00f3n en send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nLectura de tama\u00f1o 4 en la direcci\u00f3n ffff8880256fb000 por la tarea syz-executor314/4465\n\nCPU: 2 PID: 4465 Comm: syz-executor314 No contaminado 6.0.0-rc1-syzkaller #0\nNombre del hardware: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014\nRastro de Llamada:\n \u003cTAREA\u003e\n__dump_stack lib/dump_stack.c:88 [en l\u00ednea]\ndump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106\nprint_address_description mm/kasan/report.c:317 [en l\u00ednea]\nprint_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433\nkasan_report+0xb1/0x1e0 mm/kasan/report.c:495\n__create_pipe include/linux/usb.h:1945 [en l\u00ednea]\nsend_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nvfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991\nvfs_write+0x2d7/0xdd0 fs/read_write.c:576\nksys_write+0x127/0x250 fs/read_write.c:631\ndo_syscall_x64 arch/x86/entry/common.c:50 [en l\u00ednea]\ndo_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80\nentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nEl controlador iMON libera incorrectamente la referencia usb_device en\nimon_disconnect sin coordinarse con los usuarios activos del\ndispositivo.\n\nEspec\u00edficamente, los campos usbdev_intf0 y usbdev_intf1 no est\u00e1n\nprotegidos por el contador de usuarios (ictx-\u003eusers). Durante la sonda,\nimon_init_intf0 o imon_init_intf1 incrementa el contador de referencias de usb_device\ndependiendo de la interfaz. Sin embargo, durante la\ndesconexi\u00f3n, usb_put_dev se llama incondicionalmente, independientemente del\nuso real.\n\nComo resultado, si vfd_write u otras operaciones todav\u00eda est\u00e1n en\ncurso despu\u00e9s de la desconexi\u00f3n, esto puede llevar a un uso despu\u00e9s de liberaci\u00f3n del\npuntero usb_device.\n\nHilo 1 vfd_write                      Hilo 2 imon_disconnect\n                                        ...\n                                        si\n                                          usb_put_dev(ictx-\u003eusbdev_intf0)\n                                        sino\n                                          usb_put_dev(ictx-\u003eusbdev_intf1)\n...\nmientras\n  send_packet\n    si\n      pipe = usb_sndintpipe(\n        ictx-\u003eusbdev_intf0) UAF\n    sino\n      pipe = usb_sndctrlpipe(\n        ictx-\u003eusbdev_intf0, 0) UAF\n\nProteger el acceso a usbdev_intf0 y usbdev_intf1 despu\u00e9s de la desconexi\u00f3n\ncomprobando ictx-\u003edisconnected en todas las rutas de escritura. A\u00f1adir un retorno\nanticipado con -ENODEV en send_packet(), vfd_write(), lcd_write() y\ndisplay_open() si el dispositivo ya no est\u00e1 presente.\n\nEstablecer y leer ictx-\u003edisconnected bajo ictx-\u003elock para asegurar la\nsincronizaci\u00f3n de la memoria. Adquirir el bloqueo en imon_disconnect() antes de\nestablecer la bandera para sincronizar con cualquier operaci\u00f3n en curso.\n\nAsegurar que los escritores salgan anticipada y seguramente despu\u00e9s de la\ndesconexi\u00f3n antes de que el n\u00facleo USB proceda con la limpieza.\n\nEncontrado por Linux Verification Center (linuxtesting.org) con Syzkaller."
          }
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        "id": "CVE-2025-39993",
        "lastModified": "2026-10-19T21:10:00.160",
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                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: rc: fix races with imon_disconnect()\n\nSyzbot reports a KASAN issue as below:\nBUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline]\nBUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nRead of size 4 at addr ffff8880256fb000 by task syz-executor314/4465\n\nCPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014\nCall Trace:\n \u003cTASK\u003e\n__dump_stack lib/dump_stack.c:88 [inline]\ndump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106\nprint_address_description mm/kasan/report.c:317 [inline]\nprint_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433\nkasan_report+0xb1/0x1e0 mm/kasan/report.c:495\n__create_pipe include/linux/usb.h:1945 [inline]\nsend_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627\nvfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991\nvfs_write+0x2d7/0xdd0 fs/read_write.c:576\nksys_write+0x127/0x250 fs/read_write.c:631\ndo_syscall_x64 arch/x86/entry/common.c:50 [inline]\ndo_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80\nentry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThe iMON driver improperly releases the usb_device reference in\nimon_disconnect without coordinating with active users of the\ndevice.\n\nSpecifically, the fields usbdev_intf0 and usbdev_intf1 are not\nprotected by the users counter (ictx-\u003eusers). During probe,\nimon_init_intf0 or imon_init_intf1 increments the usb_device\nreference count depending on the interface. However, during\ndisconnect, usb_put_dev is called unconditionally, regardless of\nactual usage.\n\nAs a result, if vfd_write or other operations are still in\nprogress after disconnect, this can lead to a use-after-free of\nthe usb_device pointer.\n\nThread 1 vfd_write                      Thread 2 imon_disconnect\n                                        ...\n                                        if\n                                          usb_put_dev(ictx-\u003eusbdev_intf0)\n                                        else\n                                          usb_put_dev(ictx-\u003eusbdev_intf1)\n...\nwhile\n  send_packet\n    if\n      pipe = usb_sndintpipe(\n        ictx-\u003eusbdev_intf0) UAF\n    else\n      pipe = usb_sndctrlpipe(\n        ictx-\u003eusbdev_intf0, 0) UAF\n\nGuard access to usbdev_intf0 and usbdev_intf1 after disconnect by\nchecking ictx-\u003edisconnected in all writer paths. Add early return\nwith -ENODEV in send_packet(), vfd_write(), lcd_write() and\ndisplay_open() if the device is no longer present.\n\nSet and read ictx-\u003edisconnected under ictx-\u003elock to ensure memory\nsynchronization. Acquire the lock in imon_disconnect() before setting\nthe flag to synchronize with any ongoing operations.\n\nEnsure writers exit early and safely after disconnect before the USB\ncore proceeds with cleanup.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The vulnerable code is reached through an ordinary `write(2)` syscall on the `/dev/lcd0` character device (`vfd_write`/`lcd_write` \u2192 `send_packet`), i.e. a local attack surface reached via a device file, with no network exposure. The disconnect that frees the `usb_device` is a triggering condition the attacker supplies (their own removable/emulated iMON device or an unplug event), not the attack interface itself.\nAC:L - The attacker controls both sides of the race: they drive an unbounded loop of `write()` calls that hold `ictx-\u003elock` for seconds at a time (`send_packet` waits up to 10 s per packet, six packets per write) while triggering device removal, giving an extremely wide and repeatable window. Syzkaller reproduces it, and failed attempts are harmless, so it can be retried until it lands.\nPR:L - No capability, `CAP_SYS_ADMIN`, or other privilege check exists anywhere on the path \u2014 `display_open()` only checks `display_supported`/`display_isopen`, and `vfd_write`/`lcd_write` go straight to `send_packet()`. Any unprivileged process able to open the display node (routinely group-accessible on media/HTPC systems, and the node the LIRC/LCDproc userspace stack writes to) can trigger it.\nUI:N - The attacker\u0027s own process performs the writes, and the disconnect side is produced by the attacker\u0027s device or unplug action rather than by a victim. No action by another user is needed at any point.\nS:U - The use-after-free corrupts kernel memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed `struct usb_device` is read via `__create_pipe()` (`dev-\u003edevnum`) and then throughout `usb_submit_urb()` (`dev-\u003estate`, `dev-\u003eep_out[]`, `dev-\u003ebus`), so an attacker who reclaims the slab object can read back kernel data and pointers, and the UAF is a general primitive for arbitrary memory disclosure.\nI:H - The stale pointer is stored into the URB and submitted, causing `usb_get_dev(urb-\u003edev)` to write (atomic increment) into freed memory and `bus_to_hcd(urb-\u003edev-\u003ebus)-\u003edriver-\u003eurb_enqueue()` to make an indirect call through a chain rooted in attacker-reclaimable memory \u2014 a control-flow hijack and arbitrary-write primitive.\nA:H - Even without heap grooming, dereferencing and submitting an URB against a freed `usb_device` reliably produces a KASAN splat, oops, or panic, as shown in the syzbot report, and the attacker can repeat it at will."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T12:06:58.054Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/9348976003e39754af344949579e824a0a210fc4"
            },
            {
              "url": "https://git.kernel.org/stable/c/b03fac6e2a38331faf8510b480becfa90cea1c9f"
            },
            {
              "url": "https://git.kernel.org/stable/c/71c52b073922d05e79e6de7fc7f5f38f927929a4"
            },
            {
              "url": "https://git.kernel.org/stable/c/71096a6161a25e84acddb89a9d77f138502d26ab"
            },
            {
              "url": "https://git.kernel.org/stable/c/71da40648741d15b302700b68973fe8b382aef3c"
            },
            {
              "url": "https://git.kernel.org/stable/c/fd5d3e6b149ec8cce045d86a2b5e3664d6b32ba5"
            },
            {
              "url": "https://git.kernel.org/stable/c/d9f6ce99624a41c3bcb29a8d7d79b800665229dd"
            },
            {
              "url": "https://git.kernel.org/stable/c/2e7fd93b9cc565b839bc55a6662475718963e156"
            },
            {
              "url": "https://git.kernel.org/stable/c/fa0f61cc1d828178aa921475a9b786e7fbb65ccb"
            }
          ],
          "title": "media: rc: fix races with imon_disconnect()",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-39993",
        "datePublished": "2025-10-15T07:58:18.621Z",
        "dateReserved": "2025-04-16T07:20:57.150Z",
        "dateUpdated": "2026-08-05T12:06:58.054Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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