{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.177-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.95-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.3-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "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 (?:?)",
  "id": "DEBIAN-CVE-2026-63796",
  "modified": "2026-09-14T16:47:37.319844139Z",
  "published": "2026-07-19T12:16:52.033Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-63796"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-63796"
  ]
}