CVE-2026-46159: Linux kernel · btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in f407aad350bdea4db300c47433573b7a41630d33 : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:34 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in f407aad350bdea4db300c47433573b7a41630d33, f5ee467b56764964027c361641f64953fc0f8f9a, d8224b1be6627c6c3b204bfb264508d27c65ac44 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 28 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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.
References
- git.kernel.org/stable/c/f407aad350bdea4db300c47433573b7a41630d33 (opens in a new tab)
- git.kernel.org/stable/c/d8224b1be6627c6c3b204bfb264508d27c65ac44 (opens in a new tab)
- git.kernel.org/stable/c/d69a4a6813fdba7c4cc3695a7e843842b240790d (opens in a new tab)
- git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a (opens in a new tab)
- git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3 (opens in a new tab)
- git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088 (opens in a new tab)
- git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641 (opens in a new tab)
- git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)