CVE-2026-74571

CVE CVE-2026-74571EUVD EUVD-2026-59636Published 2026-08-15T12:28:10.000ZLast changed 2026-08-17T05:22:00.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: btrfs: skip global block reserve accounting for rescue mounts [BUG] Mounting with rescue=ibadroots after corrupting the block group tree root triggers a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000100 RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs] Call Trace: fill_dummy_bgs+0xd4/0x120 [btrfs] open_ctree+0xc6e/0x1ca0 [btrfs] btrfs_get_tree+0x50d/0xa40 [btrfs] The same crash occurs with a corrupted raid stripe tree root, via btrfs_read_block_groups() instead of fill_dummy_bgs(). [CAUSE] With rescue=ibadroots, btrfs_read_roots() allows the mount to continue when either root cannot be read, leaving the corresponding root pointer NULL while its on-disk feature bit remains set. btrfs_update_global_block_rsv() then dereferences the missing root based on the feature bit alone. [FIX] Rescue mounts are fully read-only and cannot start transactions, so the global reserve is never consumed. Under btrfs_is_full_ro(), mark the reserve as full and return before performing the accounting. And since we need to check if the fs is mount fully RO, export fs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h. [ Squash the fs_is_full_ro() export commit into this one. ]

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux patch: 7.1.8; 6.4.8 <6.5; 1e8087589b5cf6fa17adaf57b64cf1656d77dfec; 6.5; 8dbfc14fc736eb701089aff09645c3d4ad3decb1 <076349e4c8d11f6b58c4549976a513b2b4dc6df2; 8dbfc14fc736eb701089aff09645c3d4ad3decb1 <51a0e8399858621442807a26057bcd1cd3ced046; patch: 7.2; cbec34d3021d47007a0334c634f7053dbaf93d02; 6.1.43 <6.2; patch: 0

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Carried in the product catalogue

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Linux — Linux

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