GHSA-FQ9X-8G2W-4P5R

Vulnerability from github – Published: 2026-06-25 09:31 – Updated: 2026-06-25 09:31
VLAI
Details

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

6lowpan: fix off-by-one in multicast context address compression

The second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses &data[1] as destination and &ipaddr->s6_addr[11] as source, but both should be offset by one: &data[2] and &ipaddr->s6_addr[12] respectively.

This off-by-one has two consequences: 1. data[1] is overwritten with s6_addr[11], corrupting the RIID field in the compressed multicast address 2. data[5] is never written, so uninitialized kernel stack memory is transmitted over the network via lowpan_push_hc_data(), leaking kernel stack contents

The correct inline data layout must match what the decompression function lowpan_uncompress_multicast_ctx_daddr() expects: data[0..1] = s6_addr[1..2] (flags/scope + RIID) data[2..5] = s6_addr[12..15] (group ID)

Also zero-initialize the data array as a defensive measure against similar bugs in the future.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-53263"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-25T09:16:44Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\n6lowpan: fix off-by-one in multicast context address compression\n\nThe second memcpy in lowpan_iphc_mcast_ctx_addr_compress() uses\n\u0026data[1] as destination and \u0026ipaddr-\u003es6_addr[11] as source, but\nboth should be offset by one: \u0026data[2] and \u0026ipaddr-\u003es6_addr[12]\nrespectively.\n\nThis off-by-one has two consequences:\n1. data[1] is overwritten with s6_addr[11], corrupting the RIID\n   field in the compressed multicast address\n2. data[5] is never written, so uninitialized kernel stack memory\n   is transmitted over the network via lowpan_push_hc_data(),\n   leaking kernel stack contents\n\nThe correct inline data layout must match what the decompression\nfunction lowpan_uncompress_multicast_ctx_daddr() expects:\n  data[0..1] = s6_addr[1..2]  (flags/scope + RIID)\n  data[2..5] = s6_addr[12..15] (group ID)\n\nAlso zero-initialize the data array as a defensive measure against\nsimilar bugs in the future.",
  "id": "GHSA-fq9x-8g2w-4p5r",
  "modified": "2026-06-25T09:31:23Z",
  "published": "2026-06-25T09:31:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53263"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/06ce6fc106b16dec9b535950db626261be865e5b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2a58899d11009bffc7b4b32a571858f381121837"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4485d79617520d84ba5a14515e2b5136007d6deb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c32f30ef5e66adbfa102348e2e8a23776eb007cb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/da8808463882c3f3c357b072e25053c2121f1419"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/da8cbb64b47e9066b40af0de170901caf17b768c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dcb1bec1c32ee5c3878354e087cf5dbee2b7c7af"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f24a58c72a45f4c109f3557a760cc4b60b7a6037"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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