Use-after-free via delayed-node store reordering
Published Jan 23, 2026 · Updated Jan 23, 2026
Use-after-free in Linux kernel btrfs 6.18 before 6.18.6 allows attackers to trigger unsafe memory access through concurrent inode operations. In btrfs_get_or_create_delayed_node(), refcount_set was moved inside root->delayed_nodes locking, removing the barrier that ordered node->refs before btrfs_inode->delayed_node; another thread can therefore increment an uninitialized reference. Reachability requires active btrfs use and concurrent access to the same inode; published assessments disagree on whether the trigger is local or network reachable.
Summary
What happened
Use-after-free in Linux kernel btrfs 6.18 before 6.18.6 allows attackers to trigger unsafe memory access through concurrent inode operations. In btrfs_get_or_create_delayed_node(), refcount_set was moved inside root->delayed_nodes locking, removing the barrier that ordered node->refs before btrfs_inode->delayed_node; another thread can therefore increment an uninitialized reference. Reachability requires active btrfs use and concurrent access to the same inode; published assessments disagree on whether the trigger is local or network reachable.
The record
- CVE
- CVE-2025-71159
- Published
- Jan 23, 2026
- Updated
- Jan 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-416
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jan 23, 2026CVE publishedPublication date reported by the CVE source.
- Jan 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Is a vulnerable build present?
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- Affected versionversion=6.18
- Affected versionversion=e8513c012de75fd65e2df5499572bc6ef3f6e409 <83f59076a1ae6f5c6845d6f7ed3a1a373d883684
- Affected versionversion=e8513c012de75fd65e2df5499572bc6ef3f6e409 <c8385851a5435f4006281828d428e5d0b0bbf8af
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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Your stack
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