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.
Affected versions
Linux kernel versions
2.6.34
and later are affected. Fixed in
6.6.140,
6.12.90,
6.18.32,
7.0.7,
7.1-rc1
and their respective stable series.
References
The following references provide additional information about CVE-2026-46159 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3
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PatchKernel patch commithttps://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088
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PatchKernel patch commithttps://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77
Frequently asked questions
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What is CVE-2026-46159?
CVE-2026-46159 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 2.6.34 onward and has been patched in 6.6.140, 6.12.90, 6.18.32 and others. CVE-2026-46159 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-46159?
Yes — CVE-2026-46159 has been patched. Fixed versions include 6.6.140, 6.12.90, 6.18.32 and others. If you are running Linux kernel 2.6.34 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-46159 actively exploited?
No — CVE-2026-46159 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.