{"id":"CVE-2026-74571","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer d…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer d…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 8dbfc14fc736eb701089aff09645c3d4ad3decb1 < 969a96479add6bd42d7f7241f99f27b31571a953","Linux >= 8dbfc14fc736eb701089aff09645c3d4ad3decb1 < 076349e4c8d11f6b58c4549976a513b2b4dc6df2","Linux >= 8dbfc14fc736eb701089aff09645c3d4ad3decb1 < 51a0e8399858621442807a26057bcd1cd3ced046","Linux cbec34d3021d47007a0334c634f7053dbaf93d02","Linux 1e8087589b5cf6fa17adaf57b64cf1656d77dfec","Linux >= 6.1.43 < 6.2","Linux >= 6.4.8 < 6.5","Linux 6.5"],"published":"2026-08-15","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:17:48.057","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74571","references":[{"url":"https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/969a96479add6bd42d7f7241f99f27b31571a953","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00198,"epssPercentile":0.08859,"ingestedAt":"2026-10-15T11:00:41.671Z","slug":"CVE-2026-74571","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\n  Call Trace:\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\n   open_ctree+0xc6e/0x1ca0 [btrfs]\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\n\nThe same crash occurs with a corrupted raid stripe tree root, via\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\n\n[CAUSE]\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\nwhen either root cannot be read, leaving the corresponding root pointer\nNULL while its on-disk feature bit remains set.\n\nbtrfs_update_global_block_rsv() then dereferences the missing root based\non the feature bit alone.\n\n[FIX]\nRescue mounts are fully read-only and cannot start transactions, so the\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\nreserve as full and return before performing the accounting.\n\nAnd since we need to check if the fs is mount fully RO, export\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\n\n[ Squash the fs_is_full_ro() export commit into this one. ]\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}