{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-80537",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-80537",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-08-26T14:37:12.180Z",
    "updatedAt": "2026-08-27T05:01:27.352Z",
    "importedAt": "2026-10-24T01:58:30.346Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "xfs: fix off-by-one in rtrefcount btree root level validation",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix off-by-one in rtrefcount btree root level validation\n\nxfs_rtrefcountbt_compute_maxlevels() sets\n\n\tmp->m_rtrefc_maxlevels = min(d_maxlevels, r_maxlevels) + 1;\n\nwhere the trailing \"+ 1\" already accounts for the inode-root level, so the\ndeepest valid on-disk root level is m_rtrefc_maxlevels - 1 and a cursor must\nsatisfy bc_nlevels <= bc_maxlevels (= m_rtrefc_maxlevels).\n\nThe two on-disk validation paths, xfs_rtrefcountbt_verify() and\nxfs_iformat_rtrefcount(), check the root level with \">\" instead of \">=\", so a\ncrafted rtreflink (metadir + realtime + reflink) image whose\n/rtgroups/N.refcount inode has bb_level == m_rtrefc_maxlevels is accepted on\nmount. xfs_rtrefcountbt_init_cursor() then sets bc_nlevels = bb_level + 1,\nexceeding bc_maxlevels by one. Since the xfs_rtrefcountbt_cur slab object is\nsized for exactly bc_maxlevels entries, the first btree op on such a cursor\nindexes bc_levels[m_rtrefc_maxlevels] past the end of the object. This is\nreached by the first rtrefcount cursor built after mount, via log/CoW\nrecovery (xfs_reflink_recover_cow() during xfs_mountfs()) or an\nFS_IOC_GETFSMAP over the realtime device.\n\nReject a root level equal to m_rtrefc_maxlevels, matching the \">=\" form\nalready used by the sibling data-device refcount/rmap verifiers and the\nin-memory rtrmap verifier.\n\n  BUG: KASAN: slab-out-of-bounds in xfs_btree_lookup (fs/xfs/libxfs/xfs_btree.c:2101)\n  Write of size 2 at addr ffff888018391658 by task exploit/144\n   xfs_btree_lookup (fs/xfs/libxfs/xfs_btree.c:2101)\n   xfs_btree_query_range (fs/xfs/libxfs/xfs_btree.c:5308)\n   xfs_refcount_recover_cow_leftovers (fs/xfs/libxfs/xfs_refcount.c:2113)\n   xfs_reflink_recover_cow (fs/xfs/xfs_reflink.c:1085)\n   xlog_recover_finish (fs/xfs/xfs_log_recover.c:3551)\n   xfs_mountfs (fs/xfs/xfs_mount.c:1158)\n   xfs_fs_fill_super (fs/xfs/xfs_super.c:1940)\n   get_tree_bdev_flags (fs/super.c:1634)\n   vfs_get_tree (fs/super.c:1694)\n   path_mount (fs/namespace.c:4161)\n   __x64_sys_mount (fs/namespace.c:4367)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n  The buggy address belongs to the cache xfs_rtrefcountbt_cur of size 216\n  The buggy address is located 8 bytes to the right of\n   allocated 216-byte region [ffff888018391578, ffff888018391650)\n  Kernel panic - not syncing: Fatal exception",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "8a0ecae2ecda9f9a83a496ed05c42c4b1f5c3f2d"
            },
            {
              "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ccebfc309441e0b37b2e6ece90f18810a489d326"
            },
            {
              "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "cc3144da377de5fb422d44a2311f978623f7c900"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "6.14",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "6.14"
            },
            {
              "version": "6.18.46",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "7.1.10",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "version": "7.2",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}