CVE-2026-46159
MediumCVSS 4.7Exploitation Probability (EPSS)
Low risk1th percentile - higher than 1% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel within the btrfs_ioctl_space_info() function, which can lead to information leakage. The issue involves a TOCTOU race condition between two passes over the block group RAID type lists, resulting in the copying of uninitialized bytes to user space.
Risk Assessment
Organizations may be exposed to the leakage of sensitive data from driver memory, potentially leading to breaches of privacy and data security.
Recommendation
It is recommended to update the Linux kernel to the latest version to mitigate this vulnerability and apply patches that reduce the risk of data leakage.
Original NVD description (English source)
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.