CVE-2026-74350

Estado: RecibidaCrítica (9.8)—

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

ocfs2: validate fast symlink target during inode read

ocfs2_validate_inode_block() already rejects several inconsistent self-contained dinodes before they are exposed to the rest of the filesystem. Fast symlinks need the same treatment.

A zero-cluster symlink is treated as a fast symlink and later read through page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses strnlen() on the inline payload and then copies len + 1 bytes into the folio. If a corrupt dinode stores an i_size that does not fit the inline area or omits the terminating NUL at i_size, that copy reads past the end of the inode block buffer.

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Reject zero-cluster symlink dinodes whose i_size exceeds the inline fast-symlink capacity or whose inline payload is not NUL-terminated exactly at i_size when the inode block is validated. This keeps malformed fast symlinks from reaching the read path.

Detalles técnicos trazas, registros y código del informe original

Validation reproduced this kernel report:
KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0
RIP: 0033:0x7f5c6d859aa7
Read of size 3905
Call trace:
  dump_stack_lvl+0x66/0xa0 (?:?)
  print_report+0xce/0x630 (?:?)
  ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)
  srso_alias_return_thunk+0x5/0xfbef5 (?:?)
  __virt_addr_valid+0x19f/0x330 (?:?)
  kasan_report+0xe0/0x110 (?:?)
  kasan_check_range+0x105/0x1b0 (?:?)
  __asan_memcpy+0x23/0x60 (?:?)
  filemap_read_folio+0x27/0xe0 (?:?)
  filemap_read_folio+0x35/0xe0 (?:?)
  do_read_cache_folio+0x138/0x230 (?:?)
  __page_get_link+0x26/0x110 (?:?)
  page_get_link+0x2e/0x70 (?:?)
  vfs_readlink+0x15e/0x250 (?:?)
  touch_atime+0x4d/0x370 (?:?)
  do_readlinkat+0x186/0x200 (?:?)
  do_user_addr_fault+0x65a/0x890 (?:?)
  __x64_sys_readlink+0x46/0x60 (?:?)
  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)
  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)

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.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access75 %
Impacto principalT1499.004 Application or System Exploitationimpact65 %
Impacto secundarioT1005 Data from Local Systemcollection60 %

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N indica explotación remota sin autenticación (T1190). El kernel panic por KASAN (heap overflow) causa DoS; lectura de memoria más allá del buffer dinámico que podría exponer datos.

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

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

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

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-74350",
  "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": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
              "lessThan": "f9e2cb692b77a679b1f4cc2b7b277fa908586533",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
              "lessThan": "e234973f286ed2e8961a24561ec91594ec3e3ff8",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/ocfs2/inode.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.5"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "3.5",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/ocfs2/inode.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:36.270",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: validate fast symlink target during inode read\n\nocfs2_validate_inode_block() already rejects several inconsistent\nself-contained dinodes before they are exposed to the rest of the\nfilesystem.  Fast symlinks need the same treatment.\n\nA zero-cluster symlink is treated as a fast symlink and later read through\npage_get_link() and ocfs2_fast_symlink_read_folio().  That path uses\nstrnlen() on the inline payload and then copies len + 1 bytes into the\nfolio.  If a corrupt dinode stores an i_size that does not fit the inline\narea or omits the terminating NUL at i_size, that copy reads past the end\nof the inode block buffer.\n\nReject zero-cluster symlink dinodes whose i_size exceeds the inline\nfast-symlink capacity or whose inline payload is not NUL-terminated\nexactly at i_size when the inode block is validated.  This keeps malformed\nfast symlinks from reaching the read path.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0\nRIP: 0033:0x7f5c6d859aa7\nRead of size 3905\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xce/0x630 (?:?)\n  ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x19f/0x330 (?:?)\n  kasan_report+0xe0/0x110 (?:?)\n  kasan_check_range+0x105/0x1b0 (?:?)\n  __asan_memcpy+0x23/0x60 (?:?)\n  filemap_read_folio+0x27/0xe0 (?:?)\n  filemap_read_folio+0x35/0xe0 (?:?)\n  do_read_cache_folio+0x138/0x230 (?:?)\n  __page_get_link+0x26/0x110 (?:?)\n  page_get_link+0x2e/0x70 (?:?)\n  vfs_readlink+0x15e/0x250 (?:?)\n  touch_atime+0x4d/0x370 (?:?)\n  do_readlinkat+0x186/0x200 (?:?)\n  do_user_addr_fault+0x65a/0x890 (?:?)\n  __x64_sys_readlink+0x46/0x60 (?:?)\n  do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"
    }
  ],
  "lastModified": "2026-08-17T06:19:29.677",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}