{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-80537",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-08-26T14:34:25.765Z",
        "datePublished": "2026-08-26T14:37:12.180Z",
        "dateUpdated": "2026-08-26T14:37:12.180Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-26T14:37:12.180Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "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": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/xfs/libxfs/xfs_rtrefcount_btree.c"
                    ],
                    "versions": [
                        {
                            "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
                            "lessThan": "8a0ecae2ecda9f9a83a496ed05c42c4b1f5c3f2d",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
                            "lessThan": "ccebfc309441e0b37b2e6ece90f18810a489d326",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "9abe03a0e4f978615a2b1b484b8d09ca84c16ea0",
                            "lessThan": "cc3144da377de5fb422d44a2311f978623f7c900",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "fs/xfs/libxfs/xfs_rtrefcount_btree.c"
                    ],
                    "versions": [
                        {
                            "version": "6.14",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.14",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.46",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1.10",
                            "lessThanOrEqual": "7.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "6.18.46"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "7.1.10"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "7.2"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/8a0ecae2ecda9f9a83a496ed05c42c4b1f5c3f2d"
                },
                {
                    "url": "https://git.kernel.org/stable/c/ccebfc309441e0b37b2e6ece90f18810a489d326"
                },
                {
                    "url": "https://git.kernel.org/stable/c/cc3144da377de5fb422d44a2311f978623f7c900"
                }
            ],
            "title": "xfs: fix off-by-one in rtrefcount btree root level validation",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}