btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 3 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.34 and later | 5.10.259, 5.15.210, 6.1.176, 6.6.140, 6.12.90, 6.18.32, 7.0.7, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.34 and later Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.140, 6.12.90, 6.18.32, 7.0.7, 7.1 Patch available CNA
CPE configurations NVD · 8
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 2.6.34.1 to before 6.6.140; 6.7 to before 6.12.90; 6.13 to before 6.18.32; 6.19 to before 7.0.7 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:-:*:*:*:*:*:* | 2.6.34 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc2:*:*:*:*:*:* | 2.6.34 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc3:*:*:*:*:*:* | 2.6.34 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc4:*:*:*:*:*:* | 2.6.34 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc5:*:*:*:*:*:* | 2.6.34 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc6:*:*:*:*:*:* | 2.6.34 rc6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:2.6.34:rc7:*:*:*:*:*:* | 2.6.34 rc7 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 2.6.34.1 to before 6.6.140; 6.7 to before 6.12.90; 6.13 to before 6.18.32; 6.19 to before 7.0.7 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:-:*:*:*:*:*:* Versions 2.6.34 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc2:*:*:*:*:*:* Versions 2.6.34 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc3:*:*:*:*:*:* Versions 2.6.34 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc4:*:*:*:*:*:* Versions 2.6.34 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc5:*:*:*:*:*:* Versions 2.6.34 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc6:*:*:*:*:*:* Versions 2.6.34 rc6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:2.6.34:rc7:*:*:*:*:*:* Versions 2.6.34 rc7 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.140, 6.12.90, 6.18.32, 7.0.7, 7.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-46159
- 2026-10-03 Alias added: GHSA-8m37-fqxx-cfwj
- 2026-11-06 CISA SSVC decision points changed
References
Patch 5
- https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a
- https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3
- https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088
- https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641
- https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77
More Linux Kernel vulnerabilities
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- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
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- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2026-46159 · CVE Program
- CVE-2026-46159 · NVD
- FIRST EPSS
- GHSA-8m37-fqxx-cfwj · GitHub Advisory Database · CC BY 4.0
- CVE-2026-46159 · Red Hat security data · CC BY 4.0
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