GHSA-6CP6-7HGG-4X9M

Vulnerability from github – Published: 2026-04-01 09:31 – Updated: 2026-04-18 09:30
VLAI?
Details

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

apparmor: fix missing bounds check on DEFAULT table in verify_dfa()

The verify_dfa() function only checks DEFAULT_TABLE bounds when the state is not differentially encoded.

When the verification loop traverses the differential encoding chain, it reads k = DEFAULT_TABLE[j] and uses k as an array index without validation. A malformed DFA with DEFAULT_TABLE[j] >= state_count, therefore, causes both out-of-bounds reads and writes.

[ 57.179855] ================================================================== [ 57.180549] BUG: KASAN: slab-out-of-bounds in verify_dfa+0x59a/0x660 [ 57.180904] Read of size 4 at addr ffff888100eadec4 by task su/993

[ 57.181554] CPU: 1 UID: 0 PID: 993 Comm: su Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy) [ 57.181558] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 57.181563] Call Trace: [ 57.181572] [ 57.181577] dump_stack_lvl+0x5e/0x80 [ 57.181596] print_report+0xc8/0x270 [ 57.181605] ? verify_dfa+0x59a/0x660 [ 57.181608] kasan_report+0x118/0x150 [ 57.181620] ? verify_dfa+0x59a/0x660 [ 57.181623] verify_dfa+0x59a/0x660 [ 57.181627] aa_dfa_unpack+0x1610/0x1740 [ 57.181629] ? __kmalloc_cache_noprof+0x1d0/0x470 [ 57.181640] unpack_pdb+0x86d/0x46b0 [ 57.181647] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181653] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181656] ? aa_unpack_nameX+0x1a8/0x300 [ 57.181659] aa_unpack+0x20b0/0x4c30 [ 57.181662] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181664] ? stack_depot_save_flags+0x33/0x700 [ 57.181681] ? kasan_save_track+0x4f/0x80 [ 57.181683] ? kasan_save_track+0x3e/0x80 [ 57.181686] ? __kasan_kmalloc+0x93/0xb0 [ 57.181688] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181693] ? aa_simple_write_to_buffer+0x54/0x130 [ 57.181697] ? policy_update+0x154/0x330 [ 57.181704] aa_replace_profiles+0x15a/0x1dd0 [ 57.181707] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181710] ? __kvmalloc_node_noprof+0x44a/0x780 [ 57.181712] ? aa_loaddata_alloc+0x77/0x140 [ 57.181715] ? srso_alias_return_thunk+0x5/0xfbef5 [ 57.181717] ? _copy_from_user+0x2a/0x70 [ 57.181730] policy_update+0x17a/0x330 [ 57.181733] profile_replace+0x153/0x1a0 [ 57.181735] ? rw_verify_area+0x93/0x2d0 [ 57.181740] vfs_write+0x235/0xab0 [ 57.181745] ksys_write+0xb0/0x170 [ 57.181748] do_syscall_64+0x8e/0x660 [ 57.181762] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 57.181765] RIP: 0033:0x7f6192792eb2

Remove the MATCH_FLAG_DIFF_ENCODE condition to validate all DEFAULT_TABLE entries unconditionally.

Severity ?
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-23407"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-01T09:16:16Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix missing bounds check on DEFAULT table in verify_dfa()\n\nThe verify_dfa() function only checks DEFAULT_TABLE bounds when the state\nis not differentially encoded.\n\nWhen the verification loop traverses the differential encoding chain,\nit reads k = DEFAULT_TABLE[j] and uses k as an array index without\nvalidation. A malformed DFA with DEFAULT_TABLE[j] \u003e= state_count,\ntherefore, causes both out-of-bounds reads and writes.\n\n[   57.179855] ==================================================================\n[   57.180549] BUG: KASAN: slab-out-of-bounds in verify_dfa+0x59a/0x660\n[   57.180904] Read of size 4 at addr ffff888100eadec4 by task su/993\n\n[   57.181554] CPU: 1 UID: 0 PID: 993 Comm: su Not tainted 6.19.0-rc7-next-20260127 #1 PREEMPT(lazy)\n[   57.181558] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[   57.181563] Call Trace:\n[   57.181572]  \u003cTASK\u003e\n[   57.181577]  dump_stack_lvl+0x5e/0x80\n[   57.181596]  print_report+0xc8/0x270\n[   57.181605]  ? verify_dfa+0x59a/0x660\n[   57.181608]  kasan_report+0x118/0x150\n[   57.181620]  ? verify_dfa+0x59a/0x660\n[   57.181623]  verify_dfa+0x59a/0x660\n[   57.181627]  aa_dfa_unpack+0x1610/0x1740\n[   57.181629]  ? __kmalloc_cache_noprof+0x1d0/0x470\n[   57.181640]  unpack_pdb+0x86d/0x46b0\n[   57.181647]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   57.181653]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   57.181656]  ? aa_unpack_nameX+0x1a8/0x300\n[   57.181659]  aa_unpack+0x20b0/0x4c30\n[   57.181662]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   57.181664]  ? stack_depot_save_flags+0x33/0x700\n[   57.181681]  ? kasan_save_track+0x4f/0x80\n[   57.181683]  ? kasan_save_track+0x3e/0x80\n[   57.181686]  ? __kasan_kmalloc+0x93/0xb0\n[   57.181688]  ? __kvmalloc_node_noprof+0x44a/0x780\n[   57.181693]  ? aa_simple_write_to_buffer+0x54/0x130\n[   57.181697]  ? policy_update+0x154/0x330\n[   57.181704]  aa_replace_profiles+0x15a/0x1dd0\n[   57.181707]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   57.181710]  ? __kvmalloc_node_noprof+0x44a/0x780\n[   57.181712]  ? aa_loaddata_alloc+0x77/0x140\n[   57.181715]  ? srso_alias_return_thunk+0x5/0xfbef5\n[   57.181717]  ? _copy_from_user+0x2a/0x70\n[   57.181730]  policy_update+0x17a/0x330\n[   57.181733]  profile_replace+0x153/0x1a0\n[   57.181735]  ? rw_verify_area+0x93/0x2d0\n[   57.181740]  vfs_write+0x235/0xab0\n[   57.181745]  ksys_write+0xb0/0x170\n[   57.181748]  do_syscall_64+0x8e/0x660\n[   57.181762]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[   57.181765] RIP: 0033:0x7f6192792eb2\n\nRemove the MATCH_FLAG_DIFF_ENCODE condition to validate all DEFAULT_TABLE\nentries unconditionally.",
  "id": "GHSA-6cp6-7hgg-4x9m",
  "modified": "2026-04-18T09:30:19Z",
  "published": "2026-04-01T09:31:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23407"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/22094c996968a7c5b59cd3fc9fcbdfdd46d02fec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/555829fd91eaf0711e369b0a92aecb0f0aa3281f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a68e46dfe0c8c8ffc6f425ebc4cae6238566ecc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76b4d36c5122866452d34d8f79985e191f9c3831"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7c7cf05e0606f554c467e3a4dc49e2e578a755b4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a75e12ca90c9e70ba10fee1be2f63cdd63d91a7c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d352873bbefa7eb39995239d0b44ccdf8aaa79a4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f39e126e56c6ec1930fae51ad6bca3dae2a4c3ed"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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