# CVE-2026-90004: linux: In the Linux kernel, the following vulnerability has been resolved:  mm/damon/core: handle region split failure in ap...

CVE-2026-90004 is fixed in linux on 1 platform by DEBIAN-CVE-2026-90004 (version 7.2.6-1), released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-90004
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  mm/damon/core: handle region split failure in apply_min_nr_regions()  damon_apply_min_nr_regions() repeatedly split each region until its size becomes small enough to meet the user-defined low limit of the number of regions.  The loop assumes the split operation (damon_split_region_at()) will always succeed and create the new region.  But the operation could silently fail for memory allocation failures, for example.  If such failure happens and the region was the last region, the linked list-based next region fetching returns invalid pointer.  As a result, invalid memory dereference and corruption could happen.  Even if the corner case is handled, it imposes stress to the allocator by trying split regions for other targets.  Fix the issue by breaking all the loops for any region split failure.  This means there could be a min_nr_regions violation.  It will only rarely happen since the allocation is arguably too small to fail.  Even if it happens, it is only temporal.  damon_apply_min_nr_regions() will be called again after the aggregation interval.  The user impact of the issue should be minor, since the allocation is arguably too small to fail.  But, it could still theoretically happen, and the consequence is very bad.  This issue was discovered [1] by Sashiko.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-90004](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90004.md) | Sep 23, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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