---
id: CVE-2026-80800
title: 'nfc: llcp: bound the connect_sn TLV walk to the skb'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfc: llcp: bound the connect_sn TLV walk to the skb

  Commit 27256cdb290e ("nfc: llcp: bound SNL TLV parsing to the skb and
  add length checks") fixed the unbounded TLV w…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    e18d044bab6d3d0280639098c3fe6621692cbfe2
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    65a0ec7783b06068dda6745dd689bf4a91ee64aa
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    1964addc8dd535a05d5d3b55b4d1ac19ae31aa65
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    389986fd79e4d43f971a03b512645a1bb63c982f
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    e87527b506c40db9af528714b7b1240918eb80fc
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    22e5177ba1196a0b272a6a46c2575eb940a939c4
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    0cfbdb0e13ab5b0765d77f96af67eb879cbc9736
  - >-
    Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a <
    55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8
  - Linux 3.3
published: '2026-09-04'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:43:53.425Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80800'
references:
  - url: 'https://git.kernel.org/stable/c/b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e'
  - url: 'https://git.kernel.org/stable/c/e18d044bab6d3d0280639098c3fe6621692cbfe2'
  - url: 'https://git.kernel.org/stable/c/65a0ec7783b06068dda6745dd689bf4a91ee64aa'
  - url: 'https://git.kernel.org/stable/c/1964addc8dd535a05d5d3b55b4d1ac19ae31aa65'
  - url: 'https://git.kernel.org/stable/c/389986fd79e4d43f971a03b512645a1bb63c982f'
  - url: 'https://git.kernel.org/stable/c/e87527b506c40db9af528714b7b1240918eb80fc'
  - url: 'https://git.kernel.org/stable/c/22e5177ba1196a0b272a6a46c2575eb940a939c4'
  - url: 'https://git.kernel.org/stable/c/0cfbdb0e13ab5b0765d77f96af67eb879cbc9736'
  - url: 'https://git.kernel.org/stable/c/55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8'
tags:
  - cve.org
epss: 0.00234
epssPercentile: 0.13287
ingestedAt: '2026-10-19T09:16:01.529Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

nfc: llcp: bound the connect_sn TLV walk to the skb

Commit 27256cdb290e ("nfc: llcp: bound SNL TLV parsing to the skb and
add length checks") fixed the unbounded TLV walk in nfc_llcp_recv_snl(),
and commit d8bd2dedbde5 ("nfc: llcp: fix OOB read and u8 offset wrap in
TLV parsers") subsequently bounded nfc_llcp_parse_gb_tlv() and
nfc_llcp_parse_connection_tlv(). One sibling parser sharing the same
pattern remains unbounded: nfc_llcp_connect_sn().

nfc_llcp_connect_sn() walks a TLV list, reading a two-byte header
(type, length) followed by length bytes of value, without checking that
the two header bytes or the declared length stay within the buffer. It
returns a pointer to a service name of up to 255 bytes that may point
past the end of the skb; it is subsequently consumed by memcmp() in
nfc_llcp_sock_from_sn(). In addition tlv_array_len was computed as
"skb->len - LLCP_HEADER_SIZE" in size_t, so a CONNECT/CC frame shorter
than the LLCP header underflows to a huge length and the walk runs far
past the buffer.

nfc_llcp_connect_sn() is reachable from nfc_llcp_recv_connect() and
nfc_llcp_recv_cc(), i.e. from received CONNECT and CC PDUs. A nearby
NFC device can reach this without authentication; LLCP link activation
happens automatically after NFC-DEP, and the nfc_llcp_rx_skb()
dispatcher applies no minimum-length guard.

Walk the TLV list by pointer, bounded by skb_tail_pointer(skb), and
validate each declared length before use, matching the approach already
used for nfc_llcp_recv_snl(). Starting the walk at
&skb->data[LLCP_HEADER_SIZE] against the tail pointer also removes the
size_t underflow for short frames.

Found by 0sec automated security-research tooling (https://0sec.ai).

## Affected

- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < b2ebdfe3d5b76e91f267a61cbc3f9a0e3f77071e`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < e18d044bab6d3d0280639098c3fe6621692cbfe2`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 65a0ec7783b06068dda6745dd689bf4a91ee64aa`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 1964addc8dd535a05d5d3b55b4d1ac19ae31aa65`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 389986fd79e4d43f971a03b512645a1bb63c982f`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < e87527b506c40db9af528714b7b1240918eb80fc`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 22e5177ba1196a0b272a6a46c2575eb940a939c4`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 0cfbdb0e13ab5b0765d77f96af67eb879cbc9736`
- `Linux >= d646960f7986fefb460a2b062d5ccc8ccfeacc3a < 55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8`
- `Linux 3.3`

## Remediation

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