{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39993","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T07:20:57.150Z","datePublished":"2025-10-15T07:58:18.621Z","dateUpdated":"2026-08-05T12:06:58.054Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:06:58.054Z"},"descriptions":[{"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 <TASK>\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->users). 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->usbdev_intf0)\n                                        else\n                                          usb_put_dev(ictx->usbdev_intf1)\n...\nwhile\n  send_packet\n    if\n      pipe = usb_sndintpipe(\n        ictx->usbdev_intf0) UAF\n    else\n      pipe = usb_sndctrlpipe(\n        ictx->usbdev_intf0, 0) UAF\n\nGuard access to usbdev_intf0 and usbdev_intf1 after disconnect by\nchecking ictx->disconnected 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->disconnected under ictx->lock 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":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"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` → `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->lock` 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 — `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's own process performs the writes, and the disconnect side is produced by the attacker's 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->devnum`) and then throughout `usb_submit_urb()` (`dev->state`, `dev->ep_out[]`, `dev->bus`), 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->dev)` to write (atomic increment) into freed memory and `bus_to_hcd(urb->dev->bus)->driver->urb_enqueue()` to make an indirect call through a chain rooted in attacker-reclaimable memory — 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."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/media/rc/imon.c"],"versions":[{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"9348976003e39754af344949579e824a0a210fc4","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"b03fac6e2a38331faf8510b480becfa90cea1c9f","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"71c52b073922d05e79e6de7fc7f5f38f927929a4","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"71096a6161a25e84acddb89a9d77f138502d26ab","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"71da40648741d15b302700b68973fe8b382aef3c","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"fd5d3e6b149ec8cce045d86a2b5e3664d6b32ba5","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"d9f6ce99624a41c3bcb29a8d7d79b800665229dd","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"2e7fd93b9cc565b839bc55a6662475718963e156","status":"affected","versionType":"git"},{"version":"21677cfc562a27e099719d413287bc8d1d24deb7","lessThan":"fa0f61cc1d828178aa921475a9b786e7fbb65ccb","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/media/rc/imon.c"],"versions":[{"version":"2.6.35","status":"affected"},{"version":"0","lessThan":"2.6.35","status":"unaffected","versionType":"semver"},{"version":"5.4.301","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.246","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.195","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.156","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.110","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.51","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.16.11","lessThanOrEqual":"6.16.*","status":"unaffected","versionType":"semver"},{"version":"6.17.1","lessThanOrEqual":"6.17.*","status":"unaffected","versionType":"semver"},{"version":"6.18","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.4.301"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.10.246"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"5.15.195"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.1.156"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.6.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.12.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.16.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.17.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.35","versionEndExcluding":"6.18"}]}]}],"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"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-16T16:12:54.804332Z","id":"CVE-2025-39993","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-06-16T16:13:11.724Z"}}]}}