CVE-2026-98244
Received Received - Intake

Btrfs Free Space Tree Rebuild Failure Leads to Skipped Reference Processing

Publication date: 2026-10-06

Last updated on: 2026-10-06

Assigner: kernel.org

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.

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Meta Information

Published
2026-10-06
Last Modified
2026-10-06
Generated
2026-10-06
AI Q&A
2026-10-06
EPSS Evaluated
N/A
NVD
CVE-2026-98244
EUVD
EUVD-2026-93172

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
Linux Linux 882af9f13e830c0a4ef696bb72cd5998a5067a93
Linux Linux 882af9f13e830c0a4ef696bb72cd5998a5067a93
Linux Linux 882af9f13e830c0a4ef696bb72cd5998a5067a93
Linux Linux 6.14

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves the btrfs file system. When rebuilding the free space tree fails, the system does not properly clear a flag indicating the rebuild is in progress. This can leave the filesystem in an inconsistent state where delayed reference processing is skipped, potentially causing data integrity issues.

Detection Guidance

This vulnerability is specific to the Linux kernel's Btrfs filesystem and does not have a direct network detection method. To check if your system is affected, verify the kernel version and Btrfs-related flags. Use commands like 'uname -a' to check the kernel version and 'mount | grep btrfs' to confirm Btrfs usage. If the kernel is vulnerable, the flag BTRFS_FS_CREATING_FREE_SPACE_TREE may remain set incorrectly.

Impact Analysis

If exploited, this flaw could lead to filesystem corruption or data loss. The system may skip critical processing steps, causing inconsistencies in file metadata and free space tracking. Users might experience crashes, failed operations, or silent data corruption.

Mitigation Strategies

Update the Linux kernel to a patched version where this issue is resolved. If immediate patching is not possible, avoid using Btrfs features that rely on free space tree rebuilding. Monitor filesystem logs for errors related to Btrfs operations and consider switching to an alternative filesystem like ext4 if Btrfs is not critical.

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