What’s Vulnerable › Vulnerabilities

CVE-2026-98245: btrfs: take commit root semaphore when iterating in mark_block_group_to_copy()

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-06 · updated 2026-10-30

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.

Affected products

• Linux: 5.12 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux 7.3. Check the vendor advisory for mitigations.

References

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

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