nvdimm/btt: reject an arena whose nfree is below the lane count
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 5 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: nvdimm/btt: reject an arena whose nfree is below the lane count The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write. btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.5, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 2 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89965
- 2026-10-03 Alias added: GHSA-gj9w-7mfp-hc5m
- 2026-10-16 Affected versions changed · Red Hat
- 2026-10-16 CVSS score added · Red Hat
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-30 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/eb491343d2d1784121ad9af91c25b338c28913c3
- https://git.kernel.org/stable/c/59d5cd1f42b4bab3609512c3cb3d3540d3d21da7
- https://git.kernel.org/stable/c/f6c5313aae794ecca8f762c1a3493de5c266f120
- https://git.kernel.org/stable/c/f9bf05c63b77d000e9c01f3e47af36973887d350
- https://git.kernel.org/stable/c/6f79d1a5f2611a3d36e9312be5425cd9cb397c51
- https://git.kernel.org/stable/c/6b1faf1f099f7060b5f1f2f0d024132581f1726e
- https://git.kernel.org/stable/c/9dfa11cef4750b67591307f2c62e47a23d60e4b7
- https://git.kernel.org/stable/c/6a1f2e5ed9267ca19187038ac635393c165213ac
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Sources
- CVE-2026-89965 · CVE Program
- CVE-2026-89965 · NVD
- FIRST EPSS
- GHSA-gj9w-7mfp-hc5m · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89965 · Red Hat security data · CC BY 4.0
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