CVE-2026-89965 (CVSS 7.8)

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.

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CVSS v3.1 Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Other References

https://git.kernel.org/stable/c/59d5cd1f42b4bab3609512c3cb3d3540d3d21da7 https://git.kernel.org/stable/c/6a1f2e5ed9267ca19187038ac635393c165213ac https://git.kernel.org/stable/c/6b1faf1f099f7060b5f1f2f0d024132581f1726e https://git.kernel.org/stable/c/6f79d1a5f2611a3d36e9312be5425cd9cb397c51 https://git.kernel.org/stable/c/9dfa11cef4750b67591307f2c62e47a23d60e4b7 https://git.kernel.org/stable/c/eb491343d2d1784121ad9af91c25b338c28913c3 https://git.kernel.org/stable/c/f6c5313aae794ecca8f762c1a3493de5c266f120 https://git.kernel.org/stable/c/f9bf05c63b77d000e9c01f3e47af36973887d350

Frequently Asked Questions

What is CVE-2026-89965? +

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. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-89965? +

CVE-2026-89965 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-89965? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-89965

Description

CVSS v3.1 Score

References

Other References

Frequently Asked Questions

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