Medium 4.7Published May 28, 2026

CVE-2026-46159btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak

Updated under an hour ago (Oct 26, 2026, 9:23 PM ET)

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Exploited in the last 30 days

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.

CVSS: 4.7 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before f407aad350bdea4db300c47433573b7a41630d33; from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before d8224b1be6627c6c3b204bfb264508d27c65ac44; from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before d69a4a6813fdba7c4cc3695a7e843842b240790d; from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before f5ee467b56764964027c361641f64953fc0f8f9a; 7fde62bffb576d384ea49a3aed3403d5609ee5bc builds before 4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3; 7fde62bffb576d384ea49a3aed3403d5609ee5bc builds before 5d12e0ab009ade48c1bff9324fd9bea2c773d088; from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before d09d67d5de577cedae3de9497dff217e0ac8b641; from 7fde62bffb576d384ea49a3aed3403d5609ee5bc before 973e57c726c1f8e77259d1c8e519519f1e9aea77	CNA record
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
linux linux_kernel linux:linux_kernel	from 2.6.34.1 before 6.6.140; from 6.7 before 6.12.90; from 6.13 before 6.18.32; from 6.19 before 7.0.7; 2.6.34; 2.6.34; 2.6.34; 2.6.34; and 3 more ranges	NVD

References

References

https://git.kernel.org/stable/c/f407aad350bdea4db300c47433573b7a41630d33
https://git.kernel.org/stable/c/d8224b1be6627c6c3b204bfb264508d27c65ac44
https://git.kernel.org/stable/c/d69a4a6813fdba7c4cc3695a7e843842b240790d
https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a	patch
https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3	patch
https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088	patch
https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641	patch
https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77	patch
https://cert-portal.siemens.com/productcert/html/ssa-784472.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.