CVE-2026-63819

Estado: Pendiente de análisisAlta (7.8)—

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

f2fs: fix to do sanity check on f2fs_get_node_folio_ra()

The fuzz test will trigger above bug_on in f2fs.

The root cause should be: in the corrupted inode, there is a direct node which has the same ino and nid in its footer, so in f2fs_do_truncate_blocks(), after f2fs_get_dnode_of_data() finds such dnode: 1) ADDRS_PER_PAGE(dn.node_folio, inode) will return 923 2) once dn.ofs_in_node points to addr[923, 1017] Then it will trigger the system panic.

Let's introduce NODE_TYPE_NON_IXNODE to indicate current node should not be an inode or xattr node, and then use it in below path to detect inconsistent node chain in inode mapping table:

Detalles técnicos trazas, registros y código del informe original

kernel BUG at fs/f2fs/file.c:845!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:f2fs_do_truncate_blocks+0x1115/0x1140 fs/f2fs/file.c:845
Code: fc fc 90 0f 0b e8 8b 9d 9a fd 90 0f 0b e8 83 9d 9a fd 48 89 df 48 c7 c6 60 d1 1a 8c e8 54 f1 fc fc 90 0f 0b e8 6c 9d 9a fd 90 <0f> 0b e8 64 9d 9a fd 90 0f 0b 90 e9 93 fd ff ff e8 56 9d 9a fd 90
RSP: 0018:ffffc9000e4474c0 EFLAGS: 00010283
RAX: ffffffff842b1d34 RBX: 0000000000000003 RCX: 0000000000100000
RDX: ffffc9000f03a000 RSI: 0000000000035503 RDI: 0000000000035504
RBP: ffffc9000e447608 R08: ffff8880123b0000 R09: 0000000000000002
R10: 00000000fffffffe R11: 0000000000000002 R12: 0000000000000001
R13: 0000000000000000 R14: 1ffff92001c88ea0 R15: 00000000ffff039c
FS:  00007f7e02ee36c0(0000) GS:ffff88808c887000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff0305c4000 CR3: 0000000012d4c000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 f2fs_truncate_blocks+0x10a/0x300 fs/f2fs/file.c:882
 f2fs_truncate+0x471/0x7c0 fs/f2fs/file.c:940
 f2fs_evict_inode+0xa3f/0x1ac0 fs/f2fs/inode.c:907
 evict+0x61e/0xb10 fs/inode.c:841
 f2fs_fill_super+0x5f43/0x78f0 fs/f2fs/super.c:5224
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

	count = ADDRS_PER_PAGE(dn.node_folio, inode);

	count -= dn.ofs_in_node;
	f2fs_bug_on(sbi, count < 0);

- f2fs_do_truncate_blocks
 - f2fs_get_dnode_of_data
  - f2fs_get_node_folio_ra
   -  __get_node_folio
    - f2fs_sanity_check_node_footer
     - case NODE_TYPE_NON_IXNODE -> check whether it is inode|xnode

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.13%
Percentil entre todas las CVEs puntuadas: 2
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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact60 %

Vulnerabilidad local sin interacción (AV:L, PR:L, UI:N) en kernel Linux con impacto de confidencialidad, integridad y disponibilidad. La corrupción de nodos inode en f2fs causa panic del sistema (DoS) y potencial lectura de memoria mediante corrupción de estructuras de 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

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

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)

Mostrar

{
  "id": "CVE-2026-63819",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "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": "e05df3b115e7308afbca652769b54e4549fcc723",
              "lessThan": "406c28af75123432d38cf9bbaa6f1476f7b14770",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e05df3b115e7308afbca652769b54e4549fcc723",
              "lessThan": "0cc21c1ffe15b4156b0bf744f32fd1faef0b7c73",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e05df3b115e7308afbca652769b54e4549fcc723",
              "lessThan": "8712353ed80f87271d732297567dcdbe4b84e8c7",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/f2fs/f2fs.h",
            "fs/f2fs/node.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "3.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/f2fs/f2fs.h",
            "fs/f2fs/node.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-07-19T12:16:54.980",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0cc21c1ffe15b4156b0bf744f32fd1faef0b7c73",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/406c28af75123432d38cf9bbaa6f1476f7b14770",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8712353ed80f87271d732297567dcdbe4b84e8c7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to do sanity check on f2fs_get_node_folio_ra()\n\nkernel BUG at fs/f2fs/file.c:845!\nOops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\nCPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nRIP: 0010:f2fs_do_truncate_blocks+0x1115/0x1140 fs/f2fs/file.c:845\nCode: fc fc 90 0f 0b e8 8b 9d 9a fd 90 0f 0b e8 83 9d 9a fd 48 89 df 48 c7 c6 60 d1 1a 8c e8 54 f1 fc fc 90 0f 0b e8 6c 9d 9a fd 90 <0f> 0b e8 64 9d 9a fd 90 0f 0b 90 e9 93 fd ff ff e8 56 9d 9a fd 90\nRSP: 0018:ffffc9000e4474c0 EFLAGS: 00010283\nRAX: ffffffff842b1d34 RBX: 0000000000000003 RCX: 0000000000100000\nRDX: ffffc9000f03a000 RSI: 0000000000035503 RDI: 0000000000035504\nRBP: ffffc9000e447608 R08: ffff8880123b0000 R09: 0000000000000002\nR10: 00000000fffffffe R11: 0000000000000002 R12: 0000000000000001\nR13: 0000000000000000 R14: 1ffff92001c88ea0 R15: 00000000ffff039c\nFS:  00007f7e02ee36c0(0000) GS:ffff88808c887000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007ff0305c4000 CR3: 0000000012d4c000 CR4: 0000000000352ef0\nCall Trace:\n <TASK>\n f2fs_truncate_blocks+0x10a/0x300 fs/f2fs/file.c:882\n f2fs_truncate+0x471/0x7c0 fs/f2fs/file.c:940\n f2fs_evict_inode+0xa3f/0x1ac0 fs/f2fs/inode.c:907\n evict+0x61e/0xb10 fs/inode.c:841\n f2fs_fill_super+0x5f43/0x78f0 fs/f2fs/super.c:5224\n get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694\n vfs_get_tree+0x92/0x2a0 fs/super.c:1754\n fc_mount fs/namespace.c:1193 [inline]\n do_new_mount_fc fs/namespace.c:3758 [inline]\n do_new_mount+0x341/0xd30 fs/namespace.c:3834\n do_mount fs/namespace.c:4167 [inline]\n __do_sys_mount fs/namespace.c:4383 [inline]\n __se_sys_mount+0x31d/0x420 fs/namespace.c:4360\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n\tcount = ADDRS_PER_PAGE(dn.node_folio, inode);\n\n\tcount -= dn.ofs_in_node;\n\tf2fs_bug_on(sbi, count < 0);\n\nThe fuzz test will trigger above bug_on in f2fs.\n\nThe root cause should be: in the corrupted inode, there is a direct node\nwhich has the same ino and nid in its footer, so in f2fs_do_truncate_blocks(),\nafter f2fs_get_dnode_of_data() finds such dnode:\n1) ADDRS_PER_PAGE(dn.node_folio, inode) will return 923\n2) once dn.ofs_in_node points to addr[923, 1017]\nThen it will trigger the system panic.\n\nLet's introduce NODE_TYPE_NON_IXNODE to indicate current node should\nnot be an inode or xattr node, and then use it in below path to detect\ninconsistent node chain in inode mapping table:\n\n- f2fs_do_truncate_blocks\n - f2fs_get_dnode_of_data\n  - f2fs_get_node_folio_ra\n   -  __get_node_folio\n    - f2fs_sanity_check_node_footer\n     - case NODE_TYPE_NON_IXNODE -> check whether it is inode|xnode"
    }
  ],
  "lastModified": "2026-08-17T05:17:19.303",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}