CVE-2026-74723
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
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 9.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.55%
- Percentil entre todas las CVEs puntuadas: 44
- Fecha de la puntuación: 6/10/2026
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.
- Explotación
T1190Exploit Public-Facing Applicationinitial access75 % - Impacto principal
T1499.004Application or System Exploitationimpact70 % - Impacto secundario
T1005Data from Local Systemcollection65 %
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)
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{
"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"
}