CVE-2026-43271md-cluster: fix NULL pointer dereference in process_metadata_update
- 5.5MediumCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 5 days later
· 5 days later
Published
- 6 months later
· 6 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < b65ea893290056bee380d0c8eeb47797c2bcb311
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < dec123825c1ed74d98fd5fc7571a851dea4f46ff
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < 721599e837d3f4c0e6cc14da059612c017b6d3ec
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < dceb5a843910004cb118148e267036104fc3ee43
- affected 0ba959774e93911caff596de6391f085fb640ac4 – < f150e753cb8dd756085f46e86f2c35ce472e0a3c
- affected 4.12
- unaffected < 4.12
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.128 – ≤ 6.6.*
- unaffected 6.12.75 – ≤ 6.12.*
- unaffected 6.18.16 – ≤ 6.18.*
- unaffected 6.19.6 – ≤ 6.19.*
- unaffected 7.0 – ≤ *
References
References6
- https://git.kernel.org/stable/c/b65ea893290056bee380d0c8eeb47797c2bcb311 (opens in a new tab)
- https://git.kernel.org/stable/c/a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1 (opens in a new tab)
- https://git.kernel.org/stable/c/dec123825c1ed74d98fd5fc7571a851dea4f46ff (opens in a new tab)
- https://git.kernel.org/stable/c/721599e837d3f4c0e6cc14da059612c017b6d3ec (opens in a new tab)
- https://git.kernel.org/stable/c/dceb5a843910004cb118148e267036104fc3ee43 (opens in a new tab)
- https://git.kernel.org/stable/c/f150e753cb8dd756085f46e86f2c35ce472e0a3c (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-27666 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-43271)Record last updated .