CVE-2026-74571
Received
Received - Intake
NULL Pointer Dereference in Linux Kernel Btrfs
Vulnerability report for CVE-2026-74571, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-15
Last updated on: 2026-08-15
Assigner: kernel.org
Description
Description
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. ]
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
