GHSA-HPGR-CQMV-PHP2

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31
VLAI
Details

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

Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame()

While rfcomm_recv_frame() verifies that skb->len is at least sizeof(hdr) + 1 (4 bytes: 3-byte header + 1-byte FCS), an RFCOMM frame with an extended 2-byte length field (!__test_ea(hdr->len)) has a 4-byte header plus a 1-byte FCS (5 bytes minimum, sizeof(hdr) + 2).

When a 4-byte RFCOMM frame with EA == 0 arrives: 1. The initial skb->len < sizeof(*hdr) + 1 check passes (4 < 4 is false). 2. Trimming the FCS byte decrements skb->len to 3. 3. If __check_fcs() succeeds, skb_pull(skb, 4) fails (4 > 3) and returns NULL without advancing skb->data. 4. Because the return value of skb_pull() is ignored, the un-pulled 3-byte struct rfcomm_hdr remains at skb->data and is either queued as application payload via rfcomm_recv_data() or parsed as a multiplexer control command via rfcomm_recv_mcc() on DLCI 0.

Fix this by extending the length check in rfcomm_recv_frame() to also require skb->len >= sizeof(*hdr) + 2 when !__test_ea(hdr->len).

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98600"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:12Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame()\n\nWhile rfcomm_recv_frame() verifies that skb-\u003elen is at least\nsizeof(*hdr) + 1 (4 bytes: 3-byte header + 1-byte FCS), an RFCOMM frame\nwith an extended 2-byte length field (!__test_ea(hdr-\u003elen)) has a 4-byte\nheader plus a 1-byte FCS (5 bytes minimum, sizeof(*hdr) + 2).\n\nWhen a 4-byte RFCOMM frame with EA == 0 arrives:\n1. The initial skb-\u003elen \u003c sizeof(*hdr) + 1 check passes (4 \u003c 4 is false).\n2. Trimming the FCS byte decrements skb-\u003elen to 3.\n3. If __check_fcs() succeeds, skb_pull(skb, 4) fails (4 \u003e 3) and returns\n   NULL without advancing skb-\u003edata.\n4. Because the return value of skb_pull() is ignored, the un-pulled\n   3-byte struct rfcomm_hdr remains at skb-\u003edata and is either queued as\n   application payload via rfcomm_recv_data() or parsed as a multiplexer\n   control command via rfcomm_recv_mcc() on DLCI 0.\n\nFix this by extending the length check in rfcomm_recv_frame() to also\nrequire skb-\u003elen \u003e= sizeof(*hdr) + 2 when !__test_ea(hdr-\u003elen).",
  "id": "GHSA-hpgr-cqmv-php2",
  "modified": "2026-10-18T18:31:56Z",
  "published": "2026-10-18T18:31:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98600"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6d91041bb38b97e2feb625123cc0529d7b83a0e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/71ccacde407b7d8f0ef48974a0d2524602fd5c44"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76876fd26569302d26d91cbe8b75fa8e66cf8969"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7a1781a2f3a9667b3065d402d1f11986a2363e08"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9240fc1f2cde5331c61608da21b00394602ca762"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/97711b964877242933484989224a3c4c5d88a5ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be00deee60044ffa820f9436415caeb665b2cda0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c25587fa26761e623198b4f47151fe79d09ccde6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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