CVE-2026-43117

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Btrfs Sync File Use-After-Free via OverlayFS

Publication date: 2026-05-06

Last updated on: 2026-06-01

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file() If overlay is used on top of btrfs, dentry->d_sb translates to overlay's super block and fsid assignment will lead to a crash. Use file_inode(file)->i_sb to always get btrfs_sb.

CVSS Scores

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Meta Information

Published

2026-05-06

Last Modified

2026-06-01

Generated

2026-07-06

AI Q&A

2026-05-06

EPSS Evaluated

2026-07-05

NVD

CVE-2026-43117

EUVD

EUVD-2026-27643

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	From 6.13 (inc) to 6.18.24 (exc)
linux	linux_kernel	From 6.19 (inc) to 6.19.14 (exc)
linux	linux_kernel	From 6.7 (inc) to 6.12.83 (exc)
linux	linux_kernel	From 4.8 (inc) to 6.6.136 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Mitigation Strategies

The vulnerability has been resolved by correcting the way the superblock is retrieved in the btrfs tracepoints, specifically by using file_inode(file)->i_sb to always get the correct btrfs superblock.

To mitigate this vulnerability, you should update your Linux kernel to a version that includes this fix.

Executive Summary

This vulnerability exists in the Linux kernel's btrfs filesystem tracepoints. Specifically, when an overlay filesystem is used on top of btrfs, the code incorrectly retrieves the superblock from a dentry structure. Instead of getting the btrfs superblock, it gets the overlay's superblock, which causes incorrect fsid assignment and can lead to a system crash.

The fix involves changing the code to use file_inode(file)->i_sb to always get the correct btrfs superblock.

Impact Analysis

This vulnerability can cause a system crash when using an overlay filesystem on top of btrfs due to incorrect superblock handling. Such crashes can lead to system instability, potential data loss, and downtime.

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