CVE-2026-46159: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak...

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak btrfs_ioctl_space_info() has a TOCTOU race between two passes over the block group RAID type lists. The first pass counts entries to determine the allocation size, then the second pass fills the buffer. The groups_sem rwlock is released between passes, allowing concurrent block group removal to reduce the entry count. When the second pass fills fewer entries than the first pass counted, copy_to_user() copies the full alloc_size bytes including trailing uninitialized kmalloc bytes to userspace. Fix by copying only total_spaces entries (the actually-filled count from the second pass) instead of alloc_size bytes, and switch to kzalloc so any future copy size mismatch cannot leak heap data.

Metrics

CVSS 3.1

4.7/10

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.09%

0.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-367

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 2.6.34.1, < 6.6.140
Linux	Linux Kernel	>= 6.7, < 6.12.90
Linux	Linux Kernel	>= 6.13, < 6.18.32
Linux	Linux Kernel	>= 6.19, < 7.0.7
Linux	Linux Kernel	2.6.34

References

Timeline

Published: May 28, 2026
Last Modified: Jun 19, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-46159?

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak btrfs_ioctl_space_info() has a TOCTOU race between two passes over the block group RAID type lists. The first pass counts entries to determine the allocation size, then the second pass fills the buffer. The groups_sem rwlock is released between passes, allowing concurrent block group removal to reduce the entry count. When the second pass fills fewer entries than the first pass counted, copy_to_user() copies the full alloc_size bytes including trailing uninitialized kmalloc bytes to userspace. Fix by copying only total_spaces entries (the actually-filled count from the second pass) instead of alloc_size bytes, and switch to kzalloc so any future copy size mismatch cannot leak heap data.

How severe is CVE-2026-46159?

CVE-2026-46159 has a CVSS score of 4.7/10 (MEDIUM severity). The EPSS model estimates a 0.09% probability of exploitation in the next 30 days.

How do I fix CVE-2026-46159?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.