CVE-2026-89965
nvdimm/btt: reject an arena whose nfree is below the lane count
Description
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.
INFO
Published Date :
Sept. 16, 2026, 11:17 a.m.
Last Modified :
Sept. 16, 2026, 3:18 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Validate nfree against lane count before allocating arrays.
- Reject arenas with nfree below the lane count.
- Apply the fix to the Linux kernel's BTT subsystem.
- Update the btt.rst documentation for the invariant.
References to Advisories, Solutions, and Tools
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CVE-2026-89965.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
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stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-89965
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 16, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 16, 2026
Action Type Old Value New Value Added Description 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89965.json">CVE-2026-89965</a> Added Reference https://git.kernel.org/stable/c/59d5cd1f42b4bab3609512c3cb3d3540d3d21da7 Added Reference https://git.kernel.org/stable/c/6a1f2e5ed9267ca19187038ac635393c165213ac Added Reference https://git.kernel.org/stable/c/6b1faf1f099f7060b5f1f2f0d024132581f1726e Added Reference https://git.kernel.org/stable/c/6f79d1a5f2611a3d36e9312be5425cd9cb397c51 Added Reference https://git.kernel.org/stable/c/9dfa11cef4750b67591307f2c62e47a23d60e4b7 Added Reference https://git.kernel.org/stable/c/eb491343d2d1784121ad9af91c25b338c28913c3 Added Reference https://git.kernel.org/stable/c/f6c5313aae794ecca8f762c1a3493de5c266f120 Added Reference https://git.kernel.org/stable/c/f9bf05c63b77d000e9c01f3e47af36973887d350