CVE-2026-63905 (GCVE-0-2026-63905)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-19 14:55
VLAI
Title
usbip: vudc: Fix use after free bug in vudc_remove due to race condition
Summary
In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: Fix use after free bug in vudc_remove due to race condition This patch follows up Zheng Wang's 2023 report of a use-after-free in vudc_remove(). The original thread stalled on Shuah Khan's request for runtime testing of the unplug/unbind path. This patch supplies that testing and keeps Zheng's original fix shape. In vudc_probe(), v_init_timer() binds udc->tr_timer.timer to v_timer(). usbip_sockfd_store() starts the timer via v_start_timer()/v_kick_timer(). vudc_remove() can then free the containing struct vudc while the timer is still pending or executing. KASAN confirms the race on an unpatched x86_64 QEMU guest with CONFIG_KASAN=y, CONFIG_USBIP_VUDC=y, CONFIG_USB_ZERO=y, and a tight loop that repeatedly writes a socket fd to usbip_sockfd, closes the socket pair, and unbinds/rebinds usbip-vudc.0: BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x8ba/0x8e0 Write of size 8 at addr ffff888001b80740 by task trigger_and_unb/239 Allocated by task 239: vudc_probe+0x4d/0xaa0 Freed by task 239: kfree+0x18f/0x520 device_release_driver_internal+0x388/0x540 unbind_store+0xd9/0x100 This lands in the timer core rather than v_timer() itself because the embedded timer_list is being walked after its containing struct vudc has already been freed. The underlying lifetime bug is the same one Zheng reported. With v_stop_timer() called from vudc_remove() and the timer deleted synchronously, the same harness completed 5000 bind/unbind iterations with no KASAN report.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < 61704e5cf9cd7464b510eb606e7e2978b1160a64 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < dcc1c90b28b28b7c493547506297e78653f81952 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < 1036ac6148995feaf486014d32bf26bf993c06a9 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < a0638db2340ee053ab0450656a763fd111475e54 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < d07ed707467ce05ea9c03412d0c5ee9d0fe386a6 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < 88d459e5b5a46da1ef9fd6f52d9439343edeec88 (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < 207bf80362df3fce8ebc9723351dcb1bc6d9ed0f (git)
Affected: b6a0ca11186759ad7045d68a5447b1e89f658384 , < d96209626a29ea64666be98c30b30ac82e5f1be6 (git)
Create a notification for this product.
Linux Linux Affected: 4.7
Unaffected: 0 , < 4.7 (semver)
Unaffected: 5.10.259 , ≤ 5.10.* (semver)
Unaffected: 5.15.210 , ≤ 5.15.* (semver)
Unaffected: 6.1.176 , ≤ 6.1.* (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusbip: vudc: Fix use after free bug in vudc_remove due to race condition\n\nThis patch follows up Zheng Wang\u0027s 2023 report of a use-after-free in\nvudc_remove(). The original thread stalled on Shuah Khan\u0027s request for\nruntime testing of the unplug/unbind path. This patch supplies that\ntesting and keeps Zheng\u0027s original fix shape.\n\nIn vudc_probe(), v_init_timer() binds udc-\u003etr_timer.timer to v_timer().\nusbip_sockfd_store() starts the timer via v_start_timer()/v_kick_timer().\nvudc_remove() can then free the containing struct vudc while the timer is\nstill pending or executing.\n\nKASAN confirms the race on an unpatched x86_64 QEMU guest with\nCONFIG_KASAN=y, CONFIG_USBIP_VUDC=y, CONFIG_USB_ZERO=y, and a tight loop\nthat repeatedly writes a socket fd to usbip_sockfd, closes the socket\npair, and unbinds/rebinds usbip-vudc.0:\n\n  BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x8ba/0x8e0\n  Write of size 8 at addr ffff888001b80740 by task trigger_and_unb/239\n  Allocated by task 239:\n    vudc_probe+0x4d/0xaa0\n  Freed by task 239:\n    kfree+0x18f/0x520\n    device_release_driver_internal+0x388/0x540\n    unbind_store+0xd9/0x100\n\nThis lands in the timer core rather than v_timer() itself because the\nembedded timer_list is being walked after its containing struct vudc has\nalready been freed. The underlying lifetime bug is the same one Zheng\nreported.\n\nWith v_stop_timer() called from vudc_remove() and the timer deleted\nsynchronously, the same harness completed 5000 bind/unbind iterations\nwith no KASAN report."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-07-19T14:55:12.270Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64"
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        {
          "url": "https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6"
        }
      ],
      "title": "usbip: vudc: Fix use after free bug in vudc_remove due to race condition",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
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This patch supplies that\\ntesting and keeps Zheng\u0027s original fix shape.\\n\\nIn vudc_probe(), v_init_timer() binds udc-\u003etr_timer.timer to v_timer().\\nusbip_sockfd_store() starts the timer via v_start_timer()/v_kick_timer().\\nvudc_remove() can then free the containing struct vudc while the timer is\\nstill pending or executing.\\n\\nKASAN confirms the race on an unpatched x86_64 QEMU guest with\\nCONFIG_KASAN=y, CONFIG_USBIP_VUDC=y, CONFIG_USB_ZERO=y, and a tight loop\\nthat repeatedly writes a socket fd to usbip_sockfd, closes the socket\\npair, and unbinds/rebinds usbip-vudc.0:\\n\\n  BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x8ba/0x8e0\\n  Write of size 8 at addr ffff888001b80740 by task trigger_and_unb/239\\n  Allocated by task 239:\\n    vudc_probe+0x4d/0xaa0\\n  Freed by task 239:\\n    kfree+0x18f/0x520\\n    device_release_driver_internal+0x388/0x540\\n    unbind_store+0xd9/0x100\\n\\nThis lands in the timer core rather than v_timer() itself because the\\nembedded timer_list is being walked after its containing struct vudc has\\nalready been freed. The underlying lifetime bug is the same one Zheng\\nreported.\\n\\nWith v_stop_timer() called from vudc_remove() and the timer deleted\\nsynchronously, the same harness completed 5000 bind/unbind iterations\\nwith no KASAN report.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/usb/usbip/vudc_dev.c\",\"drivers/usb/usbip/vudc_transfer.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"61704e5cf9cd7464b510eb606e7e2978b1160a64\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"dcc1c90b28b28b7c493547506297e78653f81952\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"1036ac6148995feaf486014d32bf26bf993c06a9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"a0638db2340ee053ab0450656a763fd111475e54\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"d07ed707467ce05ea9c03412d0c5ee9d0fe386a6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"88d459e5b5a46da1ef9fd6f52d9439343edeec88\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"207bf80362df3fce8ebc9723351dcb1bc6d9ed0f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b6a0ca11186759ad7045d68a5447b1e89f658384\",\"lessThan\":\"d96209626a29ea64666be98c30b30ac82e5f1be6\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/usb/usbip/vudc_dev.c\",\"drivers/usb/usbip/vudc_transfer.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.7\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.7\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.259\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.210\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.176\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.143\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.12\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1036ac6148995feaf486014d32bf26bf993c06a9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/207bf80362df3fce8ebc9723351dcb1bc6d9ed0f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/61704e5cf9cd7464b510eb606e7e2978b1160a64\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/88d459e5b5a46da1ef9fd6f52d9439343edeec88\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d07ed707467ce05ea9c03412d0c5ee9d0fe386a6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d96209626a29ea64666be98c30b30ac82e5f1be6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dcc1c90b28b28b7c493547506297e78653f81952\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T14:03:16+00:00",
      "cve": "CVE-2026-63905",
      "id": "CVE-2026-63905",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: usbip: vudc: Fix use after free bug in vudc_remove due to race condition",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63905.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.