---
id: CVE-2026-93783
title: |-
  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 v…
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 v…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    67dc3b40fae71b6b11c71e7ff69bac0758818c05
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    b230e5bf501c5edaf2eb0991cb862ac142031d4b
  - Linux < 6.12.111
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T17:17:10.907'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93783'
references:
  - url: 'https://git.kernel.org/stable/c/67dc3b40fae71b6b11c71e7ff69bac0758818c05'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b230e5bf501c5edaf2eb0991cb862ac142031d4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T16:47:15.904Z'
---

## Overview

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).

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.