Vulnerability-Lookup

FKIE_CVE-2026-63796

Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - Updated: 2026-10-19 20:19

Severity

8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: ocfs2: reject oversized group bitmap descriptors ocfs2_validate_gd_parent() only bounds bg_bits against the parent allocator's chain geometry. A malicious descriptor can still claim a bg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in the group descriptor block, so later bitmap scans and bit updates can run past bg_bitmap. Add a physical-cap check based on ocfs2_group_bitmap_size() for the parent allocator type and reject descriptors whose bg_size or bg_bits exceed that capacity. Keep the existing chain geometry check so both the on-disk bitmap layout and the allocator metadata must agree before the descriptor is used. Validation reproduced this kernel report: KASAN use-after-free in _find_next_bit+0x7f/0xc0 Read of size 8 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xd0/0x630 (?:?) _find_next_bit+0x7f/0xc0 (?:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x188/0x2f0 (?:?) kasan_report+0xe4/0x120 (?:?) ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375) ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457) ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86) ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786) ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886) get_page_from_freelist+0x70e/0x2370 (?:?) lock_release+0xc6/0x290 (?:?) do_raw_spin_unlock+0x9a/0x100 (?:?) kasan_unpoison+0x27/0x60 (?:?) __bfs+0x147/0x240 (?:?) get_page_from_freelist+0x83d/0x2370 (?:?) ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96) sched_domains_numa_masks_clear+0x70/0xd0 (?:?) check_irq_usage+0xe8/0xb70 (?:?) __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497) check_path+0x24/0x50 (?:?) rcu_is_watching+0x20/0x50 (?:?) check_prev_add+0xfd/0xd00 (?:?) ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?) __folio_batch_add_and_move+0x1f5/0x3d0 (?:?) ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?) filemap_add_folio+0x105/0x1f0 (?:?) ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043) ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?) down_write+0xf5/0x180 (?:?) ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?) __mark_inode_dirty+0x758/0x9a0 (?:?) inode_to_bdi+0x41/0x90 (?:?) balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?) generic_perform_write+0x252/0x440 (?:?) mnt_put_write_access_file+0x16/0x70 (?:?) file_update_time_flags+0xe4/0x200 (?:?) ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?) lock_acquire+0x184/0x2f0 (?:?) ksys_write+0xd2/0x170 (?:?) apparmor_file_permission+0xf5/0x310 (?:?) read_zero+0x8d/0x140 (?:?) lock_is_held_type+0x8f/0x100 (?:?)

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/296c6a42b1174395935ca4cfe8f393e37b698d54	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/336340a0f8a141df8a4eb21a5a86f8ffb87769f6	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4cd57ebee395041099fcdfcabb00749ce38d8b27	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/8f9903b0cdbb3155a8899410330b4b4d583a7a5c	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/99c21e7263248c3f084756bfae08163cc5d6c62f	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/9bd541e09dffff27e5bec0f9f45b0228173a5375	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c5a125eadba05ba421c4b55e68da22b4a40d32b4	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/suballoc.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
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            {
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              "versionType": "git"
            },
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.16"
            },
            {
              "lessThan": "2.6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "524F7CF4-3630-49FE-B714-8F1D8D7A6185",
              "versionEndExcluding": "5.10.260",
              "versionStartIncluding": "2.6.16",
              "vulnerable": true
            },
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            {
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              "matchCriteriaId": "333C9E30-7FD4-46A2-94EF-C1AA1F3EE28B",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "C8AD3BC8-C843-423C-B9DB-CB52F67F578E",
              "versionEndExcluding": "6.6.144",
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            {
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              "matchCriteriaId": "4E206B86-E0E3-4394-A93F-39F2D50A8AA8",
              "versionEndExcluding": "6.12.95",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "FA591B28-5D62-449E-BDBE-3C9391BF070A",
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            },
            {
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              "matchCriteriaId": "9526B150-E2B3-4C6F-8AE5-1AF92B75AD9E",
              "versionEndExcluding": "7.1.3",
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              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: reject oversized group bitmap descriptors\n\nocfs2_validate_gd_parent() only bounds bg_bits against the parent\nallocator\u0027s chain geometry.  A malicious descriptor can still claim a\nbg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in\nthe group descriptor block, so later bitmap scans and bit updates can run\npast bg_bitmap.\n\nAdd a physical-cap check based on ocfs2_group_bitmap_size() for the parent\nallocator type and reject descriptors whose bg_size or bg_bits exceed that\ncapacity.  Keep the existing chain geometry check so both the on-disk\nbitmap layout and the allocator metadata must agree before the descriptor\nis used.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in _find_next_bit+0x7f/0xc0\nRead of size 8\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xd0/0x630 (?:?)\n  _find_next_bit+0x7f/0xc0 (?:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x188/0x2f0 (?:?)\n  kasan_report+0xe4/0x120 (?:?)\n  ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)\n  ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)\n  ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)\n  ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)\n  ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)\n  get_page_from_freelist+0x70e/0x2370 (?:?)\n  lock_release+0xc6/0x290 (?:?)\n  do_raw_spin_unlock+0x9a/0x100 (?:?)\n  kasan_unpoison+0x27/0x60 (?:?)\n  __bfs+0x147/0x240 (?:?)\n  get_page_from_freelist+0x83d/0x2370 (?:?)\n  ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)\n  sched_domains_numa_masks_clear+0x70/0xd0 (?:?)\n  check_irq_usage+0xe8/0xb70 (?:?)\n  __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)\n  check_path+0x24/0x50 (?:?)\n  rcu_is_watching+0x20/0x50 (?:?)\n  check_prev_add+0xfd/0xd00 (?:?)\n  ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)\n  __folio_batch_add_and_move+0x1f5/0x3d0 (?:?)\n  ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)\n  filemap_add_folio+0x105/0x1f0 (?:?)\n  ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)\n  ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)\n  down_write+0xf5/0x180 (?:?)\n  ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)\n  __mark_inode_dirty+0x758/0x9a0 (?:?)\n  inode_to_bdi+0x41/0x90 (?:?)\n  balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)\n  generic_perform_write+0x252/0x440 (?:?)\n  mnt_put_write_access_file+0x16/0x70 (?:?)\n  file_update_time_flags+0xe4/0x200 (?:?)\n  ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)\n  lock_acquire+0x184/0x2f0 (?:?)\n  ksys_write+0xd2/0x170 (?:?)\n  apparmor_file_permission+0xf5/0x310 (?:?)\n  read_zero+0x8d/0x140 (?:?)\n  lock_is_held_type+0x8f/0x100 (?:?)"
    }
  ],
  "id": "CVE-2026-63796",
  "lastModified": "2026-10-19T20:19:20.113",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-63796",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T15:30:38.017553Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-19T12:16:52.033",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/296c6a42b1174395935ca4cfe8f393e37b698d54"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/336340a0f8a141df8a4eb21a5a86f8ffb87769f6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/4cd57ebee395041099fcdfcabb00749ce38d8b27"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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    },
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      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/99c21e7263248c3f084756bfae08163cc5d6c62f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/9bd541e09dffff27e5bec0f9f45b0228173a5375"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/c5a125eadba05ba421c4b55e68da22b4a40d32b4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2026-63796 (GCVE-0-2026-63796)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-10-19 20:07

Title

ocfs2: reject oversized group bitmap descriptors

Summary

Severity

8.8 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 15:30 UTC

CWE

CWE-125 - Out-of-bounds Read

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6992 records in the last 180 days details

References

8 references

URL	Tags
https://git.kernel.org/stable/c/336340a0f8a141df8…
https://git.kernel.org/stable/c/296c6a42b11743959…
https://git.kernel.org/stable/c/d2cd59fa848f9f137…
https://git.kernel.org/stable/c/c5a125eadba05ba42…
https://git.kernel.org/stable/c/8f9903b0cdbb3155a…
https://git.kernel.org/stable/c/4cd57ebee39504109…
https://git.kernel.org/stable/c/99c21e7263248c3f0…
https://git.kernel.org/stable/c/9bd541e09dffff27e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 336340a0f8a141df8a4eb21a5a86f8ffb87769f6 (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 296c6a42b1174395935ca4cfe8f393e37b698d54 (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < c5a125eadba05ba421c4b55e68da22b4a40d32b4 (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 8f9903b0cdbb3155a8899410330b4b4d583a7a5c (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 4cd57ebee395041099fcdfcabb00749ce38d8b27 (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 99c21e7263248c3f084756bfae08163cc5d6c62f (git) Affected: ccd979bdbce9fba8412beb3f1de68a9d0171b12c , < 9bd541e09dffff27e5bec0f9f45b0228173a5375 (git)
Linux	Linux	Affected: 2.6.16 Unaffected: 0 , < 2.6.16 (semver) Unaffected: 5.10.260 , ≤ 5.10.* (semver) Unaffected: 5.15.211 , ≤ 5.15.* (semver) Unaffected: 6.1.177 , ≤ 6.1.* (semver) Unaffected: 6.6.144 , ≤ 6.6.* (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.38 , ≤ 6.18.* (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-63796",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:30:38.017553Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-125",
                "description": "CWE-125 Out-of-bounds Read",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T20:07:47.316Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/suballoc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "296c6a42b1174395935ca4cfe8f393e37b698d54",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "c5a125eadba05ba421c4b55e68da22b4a40d32b4",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "4cd57ebee395041099fcdfcabb00749ce38d8b27",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "99c21e7263248c3f084756bfae08163cc5d6c62f",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            },
            {
              "lessThan": "9bd541e09dffff27e5bec0f9f45b0228173a5375",
              "status": "affected",
              "version": "ccd979bdbce9fba8412beb3f1de68a9d0171b12c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/suballoc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.16"
            },
            {
              "lessThan": "2.6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.260",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.211",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.260",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.211",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.177",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.38",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "2.6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: reject oversized group bitmap descriptors\n\nocfs2_validate_gd_parent() only bounds bg_bits against the parent\nallocator\u0027s chain geometry.  A malicious descriptor can still claim a\nbg_size/bg_bits pair that exceeds the bitmap bytes that physically fit in\nthe group descriptor block, so later bitmap scans and bit updates can run\npast bg_bitmap.\n\nAdd a physical-cap check based on ocfs2_group_bitmap_size() for the parent\nallocator type and reject descriptors whose bg_size or bg_bits exceed that\ncapacity.  Keep the existing chain geometry check so both the on-disk\nbitmap layout and the allocator metadata must agree before the descriptor\nis used.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in _find_next_bit+0x7f/0xc0\nRead of size 8\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xd0/0x630 (?:?)\n  _find_next_bit+0x7f/0xc0 (?:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x188/0x2f0 (?:?)\n  kasan_report+0xe4/0x120 (?:?)\n  ocfs2_find_max_contig_free_bits+0x35/0x70 (fs/ocfs2/suballoc.c:1375)\n  ocfs2_block_group_set_bits+0x472/0x4b0 (fs/ocfs2/suballoc.c:1457)\n  ocfs2_cluster_group_search+0x16b/0x440 (fs/ocfs2/suballoc.c:86)\n  ocfs2_bg_discontig_fix_result+0x1ef/0x230 (fs/ocfs2/suballoc.c:1786)\n  ocfs2_search_chain+0x8f8/0x10a0 (fs/ocfs2/suballoc.c:1886)\n  get_page_from_freelist+0x70e/0x2370 (?:?)\n  lock_release+0xc6/0x290 (?:?)\n  do_raw_spin_unlock+0x9a/0x100 (?:?)\n  kasan_unpoison+0x27/0x60 (?:?)\n  __bfs+0x147/0x240 (?:?)\n  get_page_from_freelist+0x83d/0x2370 (?:?)\n  ocfs2_claim_suballoc_bits+0x38c/0xe70 (fs/ocfs2/suballoc.c:96)\n  sched_domains_numa_masks_clear+0x70/0xd0 (?:?)\n  check_irq_usage+0xe8/0xb70 (?:?)\n  __ocfs2_claim_clusters+0x18d/0x4c0 (fs/ocfs2/suballoc.c:2497)\n  check_path+0x24/0x50 (?:?)\n  rcu_is_watching+0x20/0x50 (?:?)\n  check_prev_add+0xfd/0xd00 (?:?)\n  ocfs2_add_clusters_in_btree+0x17d/0x810 (fs/ocfs2/suballoc.c:?)\n  __folio_batch_add_and_move+0x1f5/0x3d0 (?:?)\n  ocfs2_add_inode_data+0xd9/0x120 (fs/ocfs2/suballoc.c:?)\n  filemap_add_folio+0x105/0x1f0 (?:?)\n  ocfs2_write_begin_nolock+0x29f7/0x2f80 (fs/ocfs2/suballoc.c:3043)\n  ocfs2_read_inode_block+0xb5/0x110 (fs/ocfs2/suballoc.c:?)\n  down_write+0xf5/0x180 (?:?)\n  ocfs2_write_begin+0x180/0x240 (fs/ocfs2/suballoc.c:?)\n  __mark_inode_dirty+0x758/0x9a0 (?:?)\n  inode_to_bdi+0x41/0x90 (?:?)\n  balance_dirty_pages_ratelimited_flags+0xf8/0x1d0 (?:?)\n  generic_perform_write+0x252/0x440 (?:?)\n  mnt_put_write_access_file+0x16/0x70 (?:?)\n  file_update_time_flags+0xe4/0x200 (?:?)\n  ocfs2_file_write_iter+0x80a/0x1320 (fs/ocfs2/suballoc.c:?)\n  lock_acquire+0x184/0x2f0 (?:?)\n  ksys_write+0xd2/0x170 (?:?)\n  apparmor_file_permission+0xf5/0x310 (?:?)\n  read_zero+0x8d/0x140 (?:?)\n  lock_is_held_type+0x8f/0x100 (?:?)"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - OCFS2 registers `ocfs2_export_ops` and is commonly deployed on shared cluster storage exported via NFS; a remote NFS client write reaches `ocfs2_file_write_iter` \u2192 cluster allocation \u2192 the vulnerable bitmap scan without local shell access on the server.\nAC:L - Once a crafted group descriptor with oversized `bg_size`/`bg_bits` is on disk, a single file write reliably drives `ocfs2_find_max_contig_free_bits()` past `bg_bitmap`; the fix commit reproduced this deterministically under KASAN with no race or layout-dependent conditions.\nPR:L - Exploitation requires only write access to a file on the mounted OCFS2 volume (local unprivileged user) or equivalent NFS write credentials; mounting requires `CAP_SYS_ADMIN` but metadata planting on shared SAN/iSCSI LUNs is separate from the trigger privilege.\nUI:N - In the highest-impact scenario\u2014malicious group-descriptor metadata pre-placed on shared cluster storage already mounted in production\u2014the attacker triggers the bug with their own write and no additional victim action (mount, open, or click) is required at exploit time.\nS:U - The bug corrupts kernel heap memory during in-kernel filesystem allocation on the same host/NFS server; impact stays within the kernel\u2019s security authority and does not inherently cross VM, container, or IOMMU boundaries.\nC:H - Oversized `bg_bits` causes `_find_next_bit()` to read past the physical `bg_bitmap` region; the fix commit documents a KASAN use-after-free/out-of-bounds read, which is an arbitrary kernel memory read primitive under attacker-influenced scan bounds.\nI:H - The same inflated `bg_bits` drives `ocfs2_set_bit()` during `ocfs2_block_group_set_bits()`, enabling out-of-bounds writes in the group-descriptor buffer page that can be leveraged for heap corruption and control-flow hijacking.\nA:H - The reproduced KASAN fault in `_find_next_bit()` during cluster allocation on write demonstrates kernel memory corruption that causes oops/panic-level availability loss on affected nodes."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:51:01.192Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/336340a0f8a141df8a4eb21a5a86f8ffb87769f6"
        },
        {
          "url": "https://git.kernel.org/stable/c/296c6a42b1174395935ca4cfe8f393e37b698d54"
        },
        {
          "url": "https://git.kernel.org/stable/c/d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e"
        },
        {
          "url": "https://git.kernel.org/stable/c/c5a125eadba05ba421c4b55e68da22b4a40d32b4"
        },
        {
          "url": "https://git.kernel.org/stable/c/8f9903b0cdbb3155a8899410330b4b4d583a7a5c"
        },
        {
          "url": "https://git.kernel.org/stable/c/4cd57ebee395041099fcdfcabb00749ce38d8b27"
        },
        {
          "url": "https://git.kernel.org/stable/c/99c21e7263248c3f084756bfae08163cc5d6c62f"
        },
        {
          "url": "https://git.kernel.org/stable/c/9bd541e09dffff27e5bec0f9f45b0228173a5375"
        }
      ],
      "title": "ocfs2: reject oversized group bitmap descriptors",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63796",
    "datePublished": "2026-07-19T12:02:04.634Z",
    "dateReserved": "2026-07-19T07:54:57.012Z",
    "dateUpdated": "2026-10-19T20:07:47.316Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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