CVE-2026-46123 (GCVE-0-2026-46123)

Vulnerability from cvelistv5 – Published: 2026-05-28 09:35 – Updated: 2026-06-14 17:56
VLAI?
Title
Bluetooth: virtio_bt: clamp rx length before skb_put
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: clamp rx length before skb_put virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one(). Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device. The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory. Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle(). Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log. Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length.
Severity ?
7.7 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: cf2719a21fdb9d4c8e9c834d279163609bef575d , < 4236e55b2d9d1ffd3b4bdf8ebbb86e5a0a526b4a (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < fd91fa2678ab603dfb285416c1cf3843d7be1e41 (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < ed41c81d30b211a671667259c3b5feeba0e062d5 (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < 6c1730099a6fc18b183bd6c1adad3b54adcaeda9 (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < b40cdd1b1370d76e9e760af4490cb4a351cceead (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < e6b4296f170d949ebba937cf6a3f247ec9550d2c (git)
Affected: 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be , < 21bd244b6de5d2fe1063c23acc93fbdd2b20d112 (git)
Affected: 9b67438e315b925a699f0178f4a48baf3d2d6ef4 (git)
Affected: 5.15.78 , < 5.15.209 (semver)
Affected: 6.0.8 , < 6.1 (semver)
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    Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 5.15.209 , ≤ 5.15.* (semver)
Unaffected: 6.1.175 , ≤ 6.1.* (semver)
Unaffected: 6.6.140 , ≤ 6.6.* (semver)
Unaffected: 6.12.88 , ≤ 6.12.* (semver)
Unaffected: 6.18.30 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
            "drivers/bluetooth/virtio_bt.c"
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      "cpeApplicability": [
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: virtio_bt: clamp rx length before skb_put\n\nvirtbt_rx_work() calls skb_put(skb, len) where len comes directly\nfrom virtqueue_get_buf() with no validation against the buffer we\nposted to the device. The RX skb is allocated in virtbt_add_inbuf()\nand exposed to virtio as exactly 1000 bytes via sg_init_one().\n\nChecking len against skb_tailroom(skb) is not sufficient because\nalloc_skb() can leave more tailroom than the 1000 bytes actually\nhanded to the device. A malicious or buggy backend can therefore\nreport used.len between 1001 and skb_tailroom(skb), causing skb_put()\nto include uninitialized kernel heap bytes that were never written by\nthe device.\n\nThe same path also accepts len == 0, in which case skb_put(skb, 0)\nleaves the skb empty but virtbt_rx_handle() still reads the pkt_type\nbyte from skb-\u003edata, consuming uninitialized memory.\n\nDefine VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and\nsg_init_one(), and gate virtbt_rx_work() on that same constant so\nthe bound checked matches the buffer actually exposed to the device.\nReject used.len == 0 in the same gate so an empty completion can\nno longer reach virtbt_rx_handle().\n\nUse bt_dev_err_ratelimited() because the length value comes from an\nuntrusted backend that can otherwise flood the kernel log.\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened the USB 9p\ntransport against unchecked device-reported length."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-14T17:56:08.614Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4236e55b2d9d1ffd3b4bdf8ebbb86e5a0a526b4a"
        },
        {
          "url": "https://git.kernel.org/stable/c/fd91fa2678ab603dfb285416c1cf3843d7be1e41"
        },
        {
          "url": "https://git.kernel.org/stable/c/ed41c81d30b211a671667259c3b5feeba0e062d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/6c1730099a6fc18b183bd6c1adad3b54adcaeda9"
        },
        {
          "url": "https://git.kernel.org/stable/c/b40cdd1b1370d76e9e760af4490cb4a351cceead"
        },
        {
          "url": "https://git.kernel.org/stable/c/e6b4296f170d949ebba937cf6a3f247ec9550d2c"
        },
        {
          "url": "https://git.kernel.org/stable/c/21bd244b6de5d2fe1063c23acc93fbdd2b20d112"
        }
      ],
      "title": "Bluetooth: virtio_bt: clamp rx length before skb_put",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-46123",
    "datePublished": "2026-05-28T09:35:38.003Z",
    "dateReserved": "2026-05-13T15:03:33.098Z",
    "dateUpdated": "2026-06-14T17:56:08.614Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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  • 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.
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