CVE-2026-80800 (GCVE-0-2026-80800)
Vulnerability from cvelistv5
Published
2026-09-04 15:13
Modified
2026-10-19 08:43
Severity ?
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 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).
References
Impacted products
Vendor Product Version
Linux Linux Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
Version: d646960f7986fefb460a2b062d5ccc8ccfeacc3a
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfc: llcp: bound the connect_sn TLV walk to the skb\n\nCommit 27256cdb290e (\"nfc: llcp: bound SNL TLV parsing to the skb and\nadd length checks\") fixed the unbounded TLV walk in nfc_llcp_recv_snl(),\nand commit d8bd2dedbde5 (\"nfc: llcp: fix OOB read and u8 offset wrap in\nTLV parsers\") subsequently bounded nfc_llcp_parse_gb_tlv() and\nnfc_llcp_parse_connection_tlv(). One sibling parser sharing the same\npattern remains unbounded: nfc_llcp_connect_sn().\n\nnfc_llcp_connect_sn() walks a TLV list, reading a two-byte header\n(type, length) followed by length bytes of value, without checking that\nthe two header bytes or the declared length stay within the buffer. It\nreturns a pointer to a service name of up to 255 bytes that may point\npast the end of the skb; it is subsequently consumed by memcmp() in\nnfc_llcp_sock_from_sn(). In addition tlv_array_len was computed as\n\"skb-\u003elen - LLCP_HEADER_SIZE\" in size_t, so a CONNECT/CC frame shorter\nthan the LLCP header underflows to a huge length and the walk runs far\npast the buffer.\n\nnfc_llcp_connect_sn() is reachable from nfc_llcp_recv_connect() and\nnfc_llcp_recv_cc(), i.e. from received CONNECT and CC PDUs. A nearby\nNFC device can reach this without authentication; LLCP link activation\nhappens automatically after NFC-DEP, and the nfc_llcp_rx_skb()\ndispatcher applies no minimum-length guard.\n\nWalk the TLV list by pointer, bounded by skb_tail_pointer(skb), and\nvalidate each declared length before use, matching the approach already\nused for nfc_llcp_recv_snl(). Starting the walk at\n\u0026skb-\u003edata[LLCP_HEADER_SIZE] against the tail pointer also removes the\nsize_t underflow for short frames.\n\nFound by 0sec automated security-research tooling (https://0sec.ai)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:43:53.425Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
        }
      ],
      "title": "nfc: llcp: bound the connect_sn TLV walk to the skb",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80800",
    "datePublished": "2026-09-04T15:13:14.271Z",
    "dateReserved": "2026-08-26T14:34:25.793Z",
    "dateUpdated": "2026-10-19T08:43:53.425Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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