GHSA-W4QG-RH8M-6C8Q

Vulnerability from github – Published: 2026-03-26 12:30 – Updated: 2026-04-24 15:32
VLAI
Details

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

wifi: mac80211: fix NULL deref in mesh_matches_local()

mesh_matches_local() unconditionally dereferences ie->mesh_config to compare mesh configuration parameters. When called from mesh_rx_csa_frame(), the parsed action-frame elements may not contain a Mesh Configuration IE, leaving ie->mesh_config NULL and triggering a kernel NULL pointer dereference.

The other two callers are already safe: - ieee80211_mesh_rx_bcn_presp() checks !elems->mesh_config before calling mesh_matches_local() - mesh_plink_get_event() is only reached through mesh_process_plink_frame(), which checks !elems->mesh_config, too

mesh_rx_csa_frame() is the only caller that passes raw parsed elements to mesh_matches_local() without guarding mesh_config. An adjacent attacker can exploit this by sending a crafted CSA action frame that includes a valid Mesh ID IE but omits the Mesh Configuration IE, crashing the kernel.

The captured crash log:

Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: events_unbound cfg80211_wiphy_work [...] Call Trace: ? __pfx_mesh_matches_local (net/mac80211/mesh.c:65) ieee80211_mesh_rx_queued_mgmt (net/mac80211/mesh.c:1686) [...] ieee80211_iface_work (net/mac80211/iface.c:1754 net/mac80211/iface.c:1802) [...] cfg80211_wiphy_work (net/wireless/core.c:426) process_one_work (net/kernel/workqueue.c:3280) ? assign_work (net/kernel/workqueue.c:1219) worker_thread (net/kernel/workqueue.c:3352) ? __pfx_worker_thread (net/kernel/workqueue.c:3385) kthread (net/kernel/kthread.c:436) [...] ret_from_fork_asm (net/arch/x86/entry/entry_64.S:255)

This patch adds a NULL check for ie->mesh_config at the top of mesh_matches_local() to return false early when the Mesh Configuration IE is absent.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-23396"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-26T11:16:18Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: mac80211: fix NULL deref in mesh_matches_local()\n\nmesh_matches_local() unconditionally dereferences ie-\u003emesh_config to\ncompare mesh configuration parameters. When called from\nmesh_rx_csa_frame(), the parsed action-frame elements may not contain a\nMesh Configuration IE, leaving ie-\u003emesh_config NULL and triggering a\nkernel NULL pointer dereference.\n\nThe other two callers are already safe:\n  - ieee80211_mesh_rx_bcn_presp() checks !elems-\u003emesh_config before\n    calling mesh_matches_local()\n  - mesh_plink_get_event() is only reached through\n    mesh_process_plink_frame(), which checks !elems-\u003emesh_config, too\n\nmesh_rx_csa_frame() is the only caller that passes raw parsed elements\nto mesh_matches_local() without guarding mesh_config. An adjacent\nattacker can exploit this by sending a crafted CSA action frame that\nincludes a valid Mesh ID IE but omits the Mesh Configuration IE,\ncrashing the kernel.\n\nThe captured crash log:\n\nOops: general protection fault, probably for non-canonical address ...\nKASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\nWorkqueue: events_unbound cfg80211_wiphy_work\n[...]\nCall Trace:\n \u003cTASK\u003e\n ? __pfx_mesh_matches_local (net/mac80211/mesh.c:65)\n ieee80211_mesh_rx_queued_mgmt (net/mac80211/mesh.c:1686)\n [...]\n ieee80211_iface_work (net/mac80211/iface.c:1754 net/mac80211/iface.c:1802)\n [...]\n cfg80211_wiphy_work (net/wireless/core.c:426)\n process_one_work (net/kernel/workqueue.c:3280)\n ? assign_work (net/kernel/workqueue.c:1219)\n worker_thread (net/kernel/workqueue.c:3352)\n ? __pfx_worker_thread (net/kernel/workqueue.c:3385)\n kthread (net/kernel/kthread.c:436)\n [...]\n ret_from_fork_asm (net/arch/x86/entry/entry_64.S:255)\n \u003c/TASK\u003e\n\nThis patch adds a NULL check for ie-\u003emesh_config at the top of\nmesh_matches_local() to return false early when the Mesh Configuration\nIE is absent.",
  "id": "GHSA-w4qg-rh8m-6c8q",
  "modified": "2026-04-24T15:32:18Z",
  "published": "2026-03-26T12:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23396"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a4da176ae4b4e075a19c00d3e269cfd5e05a813"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/14a4fd13657a3f2489db6566f081adfb27a49c64"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/44699c6cdfce80a0f296b54ae9314461e3e41b3d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/74de6fa472b03bc8cde0a081484e9960bcbda568"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7c55a3deaf7eaaafa2546f8de7fed19382a0a116"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a90279e7f7ea0b7e923a1c5ebee9a6b78b6d1004"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c1e3f2416fb27c816ce96d747d3e784e31f4d95c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c73bb9a2d33bf81f6eecaa0f474b6c6dbe9855bd"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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