TI-2026-31450 Aliases CVE-2026-43271 GHSA-3r8g-c43c-9gw2

md-cluster: fix NULL pointer dereference in process_metadata_update

LOW 24CWE-476Published 2026-05-06 · Updated 2026-11-06

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-476.

Summary

In the Linux kernel, the following vulnerability has been resolved: md-cluster: fix NULL pointer dereference in process_metadata_update The function process_metadata_update() blindly dereferences the 'thread' pointer (acquired via rcu_dereference_protected) within the wait_event() macro. While the code comment states "daemon thread must exist", there is a valid race condition window during the MD array startup sequence (md_run): 1. bitmap_load() is called, which invokes md_cluster_ops->join(). 2. join() starts the "cluster_recv" thread (recv_daemon). 3. At this point, recv_daemon is active and processing messages. 4. However, mddev->thread (the main MD thread) is not initialized until later in md_run(). If a METADATA_UPDATED message is received from a remote node during this specific window, process_metadata_update() will be called while mddev->thread is still NULL, leading to a kernel panic. To fix this, we must validate the 'thread' pointer. If it is NULL, we release the held lock (no_new_dev_lockres) and return early, safely ignoring the update request as the array is not yet fully ready to process it.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00117 1st percentileScored 2026-11-07

Fix Partial Linux (Linux): 6.1.191, 6.6.128, 6.12.75 +3Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Linux	Linux	4.12 and later	6.1.191, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0	Patch available	CNA

Linux VendorLinux Affected 4.12 and later Fixed in 6.1.191, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	4.12 to before 6.6.128; 6.7 to before 6.12.75; 6.13 to before 6.18.16; 6.19 to before 6.19.6	Vulnerable	Linux

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 4.12 to before 6.6.128; 6.7 to before 6.12.75; 6.13 to before 6.18.16; 6.19 to before 6.19.6 Vulnerable ·Linux

Remediation

Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred

Not affected: 4 products

Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 9

Timeline

2026-10-02 Threatist record created from CVE-2026-43271
2026-10-03 Alias added: GHSA-3r8g-c43c-9gw2
2026-10-30 Fix available: Linux/[email protected], Linux/Linux@b65ea893290056bee380d0c8eeb47797c2bcb311 · CNA
2026-10-30 1 new reference · CNA
2026-11-06 CISA SSVC decision points changed

References

Patch 5

Other 1

https://git.kernel.org/stable/c/b65ea893290056bee380d0c8eeb47797c2bcb311

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Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences