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 CPE status
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)
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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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          "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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            "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."
          }
        ],
        "id": "CVE-2026-63905",
        "lastModified": "2026-07-27T17:44:23.777",
        "metrics": {},
        "published": "2026-07-19T16:17:08.260",
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            "url": "https://git.kernel.org/stable/c/a0638db2340ee053ab0450656a763fd111475e54"
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          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Awaiting Analysis"
      }
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    "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"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-10T02:30:29Z",
      "cve": "CVE-2026-63905",
      "id": "CVE-2026-63905",
      "initial_release_date": "2026-07-21T13:03:52Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "669",
      "product_status:known_not_affected": "52",
      "product_status:recommended": "250",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-63905",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63905.json",
      "version": "11"
    }
  }
}



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Tags
Taxonomy of the tags.





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

Author Source Type Date Other

Nomenclature

  • 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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.