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CVE-2026-74723

Estado: RecibidaCrítica (9.8)—

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

btrfs: lzo: reject inline extents without valid headers

[BUG] For a crafted btrfs image, the following KASAN can be triggered when reading an inline lzo compressed file extent:

[CAUSE] For an inline lzo compressed file extent, there should always be one lzo header, recording the total length of the compressed data, followed by one segment header, recording the compressed lzo payload.

But if a crafted inline lzo compressed file extent contains only an lzo header, without the segment header or payload, lzo_decompress() will still try to read the segment header, causing a read beyond the item boundary.

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Furthermore if the inline lzo compressed file extent is the first item of the leaf, it will be at the extent buffer boundary. The above out-of-boundary read will go beyond the extent buffer boundary, triggering the above KASAN report.

[FIX] Validate the total length of the inlined lzo compressed file extent, to make sure there is at least one LZO header and one segment header, and a non-zero payload.

[ Rework the commit message to remove slop ]

Detalles técnicos trazas, registros y código del informe original
  BUG: KASAN: slab-out-of-bounds in lzo_decompress+0x57d/0x700
  Read of size 4 at addr ffff888006f2e644 by task btrfs_lzo_inlin/77

  Call Trace:
   <TASK>
   dump_stack_lvl+0x5b/0x70
   print_report+0xd1/0x610
   kasan_report+0xe0/0x110
   __asan_report_load_n_noabort+0x13/0x20
   lzo_decompress+0x57d/0x700
   btrfs_decompress+0x140/0x1c0
   uncompress_inline+0x147/0x1b0
   btrfs_get_extent+0xb23/0x10a0
   btrfs_do_readpage.constprop.0+0x538/0x1ac0
   btrfs_readahead+0x32f/0x5f0
   read_pages+0x16f/0x850
   page_cache_ra_unbounded+0x296/0x490
   do_page_cache_ra+0xd9/0x130
   page_cache_sync_ra+0x3ee/0x6f0
   filemap_get_pages+0x306/0x15c0
   filemap_read+0x329/0xd00
   btrfs_file_read_iter+0x1f8/0x2b0
   vfs_read+0x4ef/0x720
   ksys_read+0xf8/0x1d0
   __x64_sys_read+0x71/0xb0
   x64_sys_call+0x1ab0/0x1b70
   do_syscall_64+0x61/0x470
   entry_SYSCALL_64_after_hwframe+0x4b/0x53
   </TASK>

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad en kernel Linux en procesamiento de imágenes btrfs malformadas (AV:N/AC:L/PR:N/UI:N). Lectura OOB causa DoS (KASAN crash) e información de memoria. Explotación remota vía imagen btrfs.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-74723",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "a6fa6fae40ec336c7df6155255ae64ebef43a8bc",
              "lessThan": "fc50b475ad27f50b4dcc98fc4c44e8802bc1b248",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a6fa6fae40ec336c7df6155255ae64ebef43a8bc",
              "lessThan": "0fa78ef637deb5dbe341582f88553a4bce496de0",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/btrfs/lzo.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.38"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.38",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/btrfs/lzo.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-22T16:16:47.323",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0fa78ef637deb5dbe341582f88553a4bce496de0",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/fc50b475ad27f50b4dcc98fc4c44e8802bc1b248",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: lzo: reject inline extents without valid headers\n\n[BUG]\nFor a crafted btrfs image, the following KASAN can be triggered when\nreading an inline lzo compressed file extent:\n\n  BUG: KASAN: slab-out-of-bounds in lzo_decompress+0x57d/0x700\n  Read of size 4 at addr ffff888006f2e644 by task btrfs_lzo_inlin/77\n\n  Call Trace:\n   <TASK>\n   dump_stack_lvl+0x5b/0x70\n   print_report+0xd1/0x610\n   kasan_report+0xe0/0x110\n   __asan_report_load_n_noabort+0x13/0x20\n   lzo_decompress+0x57d/0x700\n   btrfs_decompress+0x140/0x1c0\n   uncompress_inline+0x147/0x1b0\n   btrfs_get_extent+0xb23/0x10a0\n   btrfs_do_readpage.constprop.0+0x538/0x1ac0\n   btrfs_readahead+0x32f/0x5f0\n   read_pages+0x16f/0x850\n   page_cache_ra_unbounded+0x296/0x490\n   do_page_cache_ra+0xd9/0x130\n   page_cache_sync_ra+0x3ee/0x6f0\n   filemap_get_pages+0x306/0x15c0\n   filemap_read+0x329/0xd00\n   btrfs_file_read_iter+0x1f8/0x2b0\n   vfs_read+0x4ef/0x720\n   ksys_read+0xf8/0x1d0\n   __x64_sys_read+0x71/0xb0\n   x64_sys_call+0x1ab0/0x1b70\n   do_syscall_64+0x61/0x470\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n   </TASK>\n\n[CAUSE]\nFor an inline lzo compressed file extent, there should always be one lzo\nheader, recording the total length of the compressed data, followed by\none segment header, recording the compressed lzo payload.\n\nBut if a crafted inline lzo compressed file extent contains only an lzo\nheader, without the segment header or payload, lzo_decompress() will\nstill try to read the segment header, causing a read beyond the item\nboundary.\n\nFurthermore if the inline lzo compressed file extent is the first item\nof the leaf, it will be at the extent buffer boundary. The above\nout-of-boundary read will go beyond the extent buffer boundary,\ntriggering the above KASAN report.\n\n[FIX]\nValidate the total length of the inlined lzo compressed file extent, to\nmake sure there is at least one LZO header and one segment header, and a\nnon-zero payload.\n\n[ Rework the commit message to remove slop ]"
    }
  ],
  "lastModified": "2026-08-25T06:18:58.147",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}