CVE-2026-93783 (GCVE-0-2026-93783)
Vulnerability from cvelistv5
Published
2026-09-24 16:02
Modified
2026-10-03 10:57
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame rfcomm_recv_frame() casts skb->data to struct rfcomm_hdr and dereferences hdr->addr and hdr->ctrl without validating skb->len first. A truncated frame with skb->len less than the minimum header size causes an out-of-bounds read of uninitialized memory. Additionally, a zero-length frame causes skb->len-- to underflow to UINT_MAX, making skb_tail_pointer() read far past the buffer. Commit 23882b828c3c ("Bluetooth: RFCOMM: validate skb length in MCC handlers") fixed the same class of missing-length-check bugs in the MCC sub-handlers, but the top-level rfcomm_recv_frame() was left unfixed. KMSAN reports: BUG: KMSAN: uninit-value in rfcomm_run ... Uninit was created at: __alloc_skb+0x474/0xb60 vhci_write+0xe9/0x870 Fix this by rejecting frames smaller than sizeof(struct rfcomm_hdr) + 1 (the minimum frame must have a 3-byte header and a 1-byte FCS).
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/rfcomm/core.c"
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          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
              "lessThan": "2.6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.271",
                  "versionStartIncluding": "2.6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.222",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: validate skb length in rfcomm_recv_frame\n\nrfcomm_recv_frame() casts skb-\u003edata to struct rfcomm_hdr and dereferences\nhdr-\u003eaddr and hdr-\u003ectrl without validating skb-\u003elen first. A truncated\nframe with skb-\u003elen less than the minimum header size causes an\nout-of-bounds read of uninitialized memory. Additionally, a zero-length\nframe causes skb-\u003elen-- to underflow to UINT_MAX, making\nskb_tail_pointer() read far past the buffer.\n\nCommit 23882b828c3c (\"Bluetooth: RFCOMM: validate skb length in MCC\nhandlers\") fixed the same class of missing-length-check bugs in the MCC\nsub-handlers, but the top-level rfcomm_recv_frame() was left unfixed.\nKMSAN reports:\n\n  BUG: KMSAN: uninit-value in rfcomm_run\n  ...\n  Uninit was created at:\n    __alloc_skb+0x474/0xb60\n    vhci_write+0xe9/0x870\n\nFix this by rejecting frames smaller than sizeof(struct rfcomm_hdr) + 1\n(the minimum frame must have a 3-byte header and a 1-byte FCS)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-03T10:57:18.054Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fb40eda15122f6b780228639c1ead6820340ff54"
        },
        {
          "url": "https://git.kernel.org/stable/c/3829af5fab5a22405bf1e7d69068c2ec0fce46ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/b161eacd7fa4a2d765724b5504ac6cc388e48f80"
        },
        {
          "url": "https://git.kernel.org/stable/c/30d1d9f3495463f7c026e4c553127f79b486fcd6"
        },
        {
          "url": "https://git.kernel.org/stable/c/67dc3b40fae71b6b11c71e7ff69bac0758818c05"
        },
        {
          "url": "https://git.kernel.org/stable/c/bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51"
        },
        {
          "url": "https://git.kernel.org/stable/c/b230e5bf501c5edaf2eb0991cb862ac142031d4b"
        }
      ],
      "title": "Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93783",
    "datePublished": "2026-09-24T16:02:17.149Z",
    "dateReserved": "2026-09-18T17:59:28.788Z",
    "dateUpdated": "2026-10-03T10:57:18.054Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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