CVE-2026-43288

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2026-05-08. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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: 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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
3.0%
KEV
Not listed

Published

May 8, 2026

Last Modified

May 15, 2026

Advisory Details (5)

Auto-updated Jun 15, 2026
No patch confirmed yet.
generic

ext4: move ext4_percpu_param_init() before ext4_mb_init() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bf5b609524497c195f801cd5707252384aed8149
generic

ext4: move ext4_percpu_param_init() before ext4_mb_init() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/aec095f3cc6cf209effd93278ce35be27db81d73
generic

ext4: move ext4_percpu_param_init() before ext4_mb_init() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9e9fb259bcddf459a0168f4a964e979e500a68a5
generic

ext4: move ext4_percpu_param_init() before ext4_mb_init() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/270564513489d98b721a1e4a10017978d5213bff
generic

ext4: move ext4_percpu_param_init() before ext4_mb_init() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0d5fcb063cdabb9aeaa8554b7fedad2092c4150e

Vendor Advisories for CVE-2026-43288(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 6.6.128—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:14 UTCEG score recompute
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  25. 2026-06-28 05:11 UTCGHSA enrichment
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  1. 2026-06-28 04:56 UTCEPSS rescore
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  3. 2026-06-26 21:36 UTCGHSA enrichment
  4. 2026-06-25 13:49 UTCEPSS rescore
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  17. 2026-06-17 02:06 UTCGHSA enrichment
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  20. 2026-06-15 02:27 UTCGHSA enrichment
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  26. 2026-06-12 01:20 UTCGHSA enrichment
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  29. 2026-06-10 22:18 UTCEPSS rescore
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  32. 2026-06-10 02:34 UTCGHSA enrichment
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  34. 2026-06-08 14:17 UTCEPSS rescore
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  36. 2026-06-08 03:49 UTCGHSA enrichment
  37. 2026-06-07 15:25 UTCEPSS rescore
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  39. 2026-06-07 04:27 UTCGHSA enrichment
  40. 2026-06-06 13:47 UTCEPSS rescore
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  42. 2026-06-06 05:04 UTCGHSA enrichment
  43. 2026-06-05 22:47 UTCEPSS rescore
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  46. 2026-06-05 05:41 UTCGHSA enrichment
  47. 2026-06-04 13:12 UTCEPSS rescore
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  49. 2026-06-04 06:18 UTCGHSA enrichment
  50. 2026-06-03 06:54 UTCGHSA enrichment
  51. 2026-06-02 20:13 UTCEPSS rescore
  52. 2026-06-02 07:31 UTCGHSA enrichment
  53. 2026-06-01 13:52 UTCEPSS rescore
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  56. 2026-05-31 22:30 UTCEPSS rescore
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  70. 2026-05-20 13:44 UTCEG score recompute
  71. 2026-05-20 13:44 UTCGHSA enrichment
  72. 2026-05-20 11:22 UTCEPSS rescore
  73. 2026-05-20 11:22 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-43288?
CVE-2026-43288 is a medium vulnerability published on May 8, 2026. In the Linux kernel, the following vulnerability has been resolved: ext4: move ext4percpuparaminit() before ext4mb_init() When running kvm-xfstests -c ext4/1k -C 1 generic/383 with the DOUBLE_CHECK macro defined, the following panic is triggered:…
When was CVE-2026-43288 disclosed?
CVE-2026-43288 was first published in the National Vulnerability Database on May 8, 2026, with the most recent update on May 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-43288 actively exploited?
CVE-2026-43288 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-43288?
CVE-2026-43288 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-43288?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-43288, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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