CVE-2026-89965: Linux

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux: from 4.2, before 5.10.270 (fixed in 5.10.270); from 5.11, before 5.15.221 (fixed in 5.15.221); from 5.16, before 6.1.188 (fixed in 6.1.188); from 6.2, before 6.6.157 (fixed in 6.6.157); from 6.7, before 6.12.110 (fixed in 6.12.110); from 6.13, before 6.18.51 (fixed in 6.18.51); …

Published 2026-09-16. Last modified 2026-09-16.