CVE-2025-38370: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix failure to rebuild free space tree using multiple transactions If we are rebuil

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix failure to rebuild free space tree using multiple transactions If we are rebuil

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix failure to rebuild free space tree using multiple transactions If we are rebuilding a free space tree, while modifying the free space tree we may need to allocate a new metadata block group. If we end up using multiple transactions for the rebuild, when we call btrfs_end_transaction() we enter btrfs_create_pending_block_groups() which calls add_block_group_free_space() to add items to the free space tree for the block group. Then later during the free space tree rebuild, at btrfs_rebuild_free_space_tree(), we may find such new block groups and call populate_free_space_tree() for them, which fails with -EEXIST because there are already items in the free space tree. Then we abort the transaction with -EEXIST at btrfs_rebuild_free_space_tree(). Notice that we say "may find" the new block groups because a new block group may be inserted in the block groups rbtree, which is being iterated by the rebuild process, before or after the current node where the rebuild process is currently at. Syzbot recently reported such case which produces a trace like the following: ------------[ cut here ]------------

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 0.15%, higher than 4% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 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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