dbcve.org
Linux KernelOperating system · Linux

CVE-2026-43288

MEDIUM · 5.5 CVSS v3.1 Published 2026-05-08
Fix available
A fix is available. Upgrade to 6.6.128 / 6.12.75 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ext4: move ext4_percpu_param_init() before ext4_mb_init() When running `kvm-xfstests -c ext4/1k -C 1 generic/383` with the `DOUBLE_CHECK` macro defined, the following panic is triggered: ================================================================== EXT4-fs error (device vdc): ext4_validate_block_bitmap:423: comm mount: bg 0: bad block bitmap checksum BUG: unable to handle page fault for address: ff110000fa2cc000 PGD 3e01067 P4D 3e02067 PUD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 2386 Comm: mount Tainted: G W 6.18.0-gba65a4e7120a-dirty #1152 PREEMPT(none) RIP: 0010:percpu_counter_add_batch+0x13/0xa0 Call Trace: <TASK> ext4_mark_group_bitmap_corrupted+0xcb/0xe0 ext4_validate_block_bitmap+0x2a1/0x2f0 ext4_read_block_bitmap+0x33/0x50 mb_group_bb_bitmap_alloc+0x33/0x80 ext4_mb_add_groupinfo+0x190/0x250 ext4_mb_init_backend+0x87/0x290 ext4_mb_init+0x456/0x640 __ext4_fill_super+0x1072/0x1680 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 vfs_cmd_create+0x59/0xe0 __do_sys_fsconfig+0x4f6/0x6b0 do_syscall_64+0x50/0x1f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== This issue can be reproduced using the following commands: mkfs.ext4 -F -q -b 1024 /dev/sda 5G tune2fs -O quota,project /dev/sda mount /dev/sda /tmp/test With DOUBLE_CHECK defined, mb_group_bb_bitmap_alloc() reads and validates the block bitmap. When the validation fails, ext4_mark_group_bitmap_corrupted() attempts to update sbi->s_freeclusters_counter. However, this percpu_counter has not been initialized yet at this point, which leads to the panic described above. Fix this by moving the execution of ext4_percpu_param_init() to occur before ext4_mb_init(), ensuring the per-CPU counters are initialized before they are used.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-908

Memory or a resource is used before it has been initialised, so its contents are whatever happened to be there — sometimes leaking earlier data, sometimes values an attacker can influence. Behaviour becomes unpredictable and occasionally exploitable. Remediation is initialising every resource before use and ensuring initialisation happens on all code paths.

General guidance for the use of uninitialized resource class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 3.17, < 6.6.128>= 6.7, < 6.12.75>= 6.13, < 6.18.16>= 6.19, < 6.19.6= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.128 / 6.12.75 / 6.18.16 or later
Fixed in 6.6.1286.12.756.18.16
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.6.128+, 6.12.75+, 6.18.16+, or 6.19.6+ depending on your current branch

  1. Identify your current kernel version using `uname -r` or `cat /proc/version`
  2. Locate the appropriate upgrade path based on your current kernel branch (6.6.x, 6.7-6.11.x, 6.12-6.17.x, 6.18.x, or 6.19.x)
  3. Upgrade to a fixed kernel version: 6.6.128 or later (for 6.6.x branch), 6.12.75 or later (for 6.12-6.17.x branch), 6.18.16 or later (for 6.18.x branch), or 6.19.6 or later (for 6.19.x branch)
  4. Reboot the system to load the patched kernel
  5. Verify the fix is applied by checking kernel version with `uname -r`
Caveat Low risk - this is a bugfix that corrects initialization order with no functional changes to the filesystem

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-43288 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43288 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data