GHSA-C2HF-FH99-25VQ

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

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

6lowpan: fix NHC entry use-after-free on error path

lowpan_nhc_do_uncompression() looks up an NHC descriptor while holding lowpan_nhc_lock. If the descriptor has no uncompress callback, the error path drops the lock before printing nhc->name.

lowpan_nhc_del() removes descriptors under the same lock and then relies on synchronize_net() before the owning module can be unloaded. That only waits for net RX RCU readers. lowpan_header_decompress() is also exported and can be reached from callers that are not necessarily covered by the net core RX critical section, for example the Bluetooth 6LoWPAN L2CAP receive path.

This leaves a race where one task drops lowpan_nhc_lock in the error path, another task unregisters and frees the matching descriptor after synchronize_net() returns, and the first task then dereferences nhc->name for the warning.

With the post-unlock window widened, KASAN reports:

BUG: KASAN: slab-use-after-free in lowpan_nhc_do_uncompression+0x1f4/0x220 Read of size 8 lowpan_nhc_do_uncompression lowpan_header_decompress

Fix this by printing the warning before dropping lowpan_nhc_lock, so the descriptor name is read while unregister is still excluded. The malformed packet is still rejected with -ENOTSUPP.

Severity
7.1 (High)
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64452"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:30Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\n6lowpan: fix NHC entry use-after-free on error path\n\nlowpan_nhc_do_uncompression() looks up an NHC descriptor while holding\nlowpan_nhc_lock.  If the descriptor has no uncompress callback, the error\npath drops the lock before printing nhc-\u003ename.\n\nlowpan_nhc_del() removes descriptors under the same lock and then relies\non synchronize_net() before the owning module can be unloaded.  That only\nwaits for net RX RCU readers.  lowpan_header_decompress() is also exported\nand can be reached from callers that are not necessarily covered by the net\ncore RX critical section, for example the Bluetooth 6LoWPAN L2CAP receive\npath.\n\nThis leaves a race where one task drops lowpan_nhc_lock in the error path,\nanother task unregisters and frees the matching descriptor after\nsynchronize_net() returns, and the first task then dereferences nhc-\u003ename\nfor the warning.\n\nWith the post-unlock window widened, KASAN reports:\n\n  BUG: KASAN: slab-use-after-free in lowpan_nhc_do_uncompression+0x1f4/0x220\n  Read of size 8\n  lowpan_nhc_do_uncompression\n  lowpan_header_decompress\n\nFix this by printing the warning before dropping lowpan_nhc_lock, so the\ndescriptor name is read while unregister is still excluded.  The malformed\npacket is still rejected with -ENOTSUPP.",
  "id": "GHSA-c2hf-fh99-25vq",
  "modified": "2026-07-27T06:30:39Z",
  "published": "2026-07-25T12:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64452"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0beccbcf50de125be5520d0ffc59af4bb8655482"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1720db928e5a58ca7d75ac1d514c3b73fd7061a7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/593b78bb3c7ef0c6e9ae6fdf5afa80a5f7573168"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/80b5c8779acee0550845394fb3e5176a398aa24c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9c2f5c0829a8c8b904dae36be6d8056b719ac605"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a8e3a94711134e898c6021a6b77374efa91b3639"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b713aa0cc344f10f7a9928a230b5f5e780d04078"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc27aea4d454abfb385ee2c9499c78b96db9b728"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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