GHSA-XV96-C36M-QHM7
Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-24 18:31In 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).
{
"affected": [],
"aliases": [
"CVE-2026-93783"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-24T17:17:10Z",
"severity": null
},
"details": "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).",
"id": "GHSA-xv96-c36m-qhm7",
"modified": "2026-09-24T18:31:28Z",
"published": "2026-09-24T18:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93783"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/67dc3b40fae71b6b11c71e7ff69bac0758818c05"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b230e5bf501c5edaf2eb0991cb862ac142031d4b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51"
}
],
"schema_version": "1.4.0",
"severity": []
}
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