CVE-2026-89573: 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

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() c

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.

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.13%, higher than 2% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 28, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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