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CVE-2025-40205 is an out-of-bounds write vulnerability in the Linux kernel Btrfs file-handle encoding function btrfs_encode_fh(). The function reports required buffer sizes of 20 or 32 bytes but can write a 40-byte connectable-root file handle when a parent exists and its root ID differs from the inode's root ID. If *max_len is insufficient, the assignment to fid->parent_root_objectid causes an 8-byte out-of-bounds write, potentially corrupting kernel memory. The flaw was introduced in Linux kernel 2.6.29. Practical triggering remains uncertain and is described as difficult.
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A memory-corruption vulnerability in the Linux kernel's Btrfs btrfs_encode_fh() function caused by incorrect file-handle size accounting and insufficient buffer-length validation. The content notes that triggering the flaw does not appear easy. It lists a CVSS v3 base score of 7.8 with local access and low privileges required. The fix checks the correct size for all three file-handle cases before writing data.
A Linux kernel Btrfs vulnerability in btrfs_encode_fh() that can cause an out-of-bounds write due to incorrect file handle size accounting, leading to potential memory corruption.
A Linux kernel Btrfs vulnerability in btrfs_encode_fh() that can cause an 8-byte out-of-bounds write due to incorrect size handling across file handle encoding cases, leading to potential memory corruption.
A potential out-of-bounds write in the Linux kernel Btrfs filesystem's btrfs_encode_fh() implementation, where the first size calculation can return a smaller handle length than the second call writes when parent and inode root IDs differ, causing an 8-byte kernel out-of-bounds write.
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