CVE-2026-43288

Kernel panic via uninitialized ext4 per-CPU counter

Published May 8, 2026 · Updated May 8, 2026

Denial of service in Linux Kernel ext4 allows local users to crash the kernel by mounting an ext4 filesystem with a bad block bitmap. During ext4 initialization, mb_group_bb_bitmap_alloc() validates the block bitmap before ext4_percpu_param_init() initializes sbi->s_freeclusters_counter, so the error path updates an uninitialized counter. Reachability requires local mount privileges, an ext4 filesystem whose bitmap validation fails, and a kernel built with DOUBLE_CHECK; the resulting page fault panics the host.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Kernel ext4 allows local users to crash the kernel by mounting an ext4 filesystem with a bad block bitmap. During ext4 initialization, mb_group_bb_bitmap_alloc() validates the block bitmap before ext4_percpu_param_init() initializes sbi->s_freeclusters_counter, so the error path updates an uninitialized counter. Reachability requires local mount privileges, an ext4 filesystem whose bitmap validation fails, and a kernel built with DOUBLE_CHECK; the resulting page fault panics the host.

The record

CVE
CVE-2026-43288
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-908, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0d5fcb063cdabb9aeaa8554b7fedad2092c4150e
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <270564513489d98b721a1e4a10017978d5213bff
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9e9fb259bcddf459a0168f4a964e979e500a68a5
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <aec095f3cc6cf209effd93278ce35be27db81d73
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bf5b609524497c195f801cd5707252384aed8149

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0d5fcb063cdabb9aeaa8554b7fedad2092c4150e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <270564513489d98b721a1e4a10017978d5213bff; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9e9fb259bcddf459a0168f4a964e979e500a68a5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <aec095f3cc6cf209effd93278ce35be27db81d73; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bf5b609524497c195f801cd5707252384aed8149

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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