CVE-2026-74571
btrfs: skip global block reserve accounting for rescue mounts
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. ]
INFO
Published Date :
Aug. 15, 2026, 1:18 p.m.
Last Modified :
Aug. 15, 2026, 1:18 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-74571
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Apply Linux kernel patches for btrfs.
- Update the Linux kernel to a patched version.
- Ensure rescue mounts are handled correctly.
- Mark reserve as full for read-only mounts.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-74571.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2 | |
| https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-74571 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-74571
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-74571 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-74571 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '8dbfc14fc736eb701089aff09645c3d4ad3decb1', 'lessThan': '076349e4c8d11f6b58c4549976a513b2b4dc6df2', 'versionType': 'git'}, {'status': 'affected', 'version': '8dbfc14fc736eb701089aff09645c3d4ad3decb1', 'lessThan': '51a0e8399858621442807a26057bcd1cd3ced046', 'versionType': 'git'}, {'status': 'affected', 'version': 'cbec34d3021d47007a0334c634f7053dbaf93d02', 'versionType': 'git'}, {'status': 'affected', 'version': '1e8087589b5cf6fa17adaf57b64cf1656d77dfec', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.43', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.4.8', 'lessThan': '6.5', 'versionType': 'semver'}], 'programFiles': ['fs/btrfs/block-rsv.c', 'fs/btrfs/disk-io.c', 'fs/btrfs/fs.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.5'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.5', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.8', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc6', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/btrfs/block-rsv.c', 'fs/btrfs/disk-io.c', 'fs/btrfs/fs.h'], 'defaultStatus': 'affected'}] Added 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. ] Added Reference https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2 Added Reference https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046