CVE-2026-63817
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.13%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode. That inode only exists when the compress_cache mount option is enabled. When compress_cache is disabled, max_nid is outside the valid inode range. A corrupted directory entry that points to ino == max_nid should therefore be rejected by f2fs_check_nid_range(). However, is_meta_ino() currently treats F2FS_COMPRESS_INO() as a meta inode unconditionally, so f2fs_iget() bypasses do_read_inode() and its nid range check, and instantiates a fake internal inode instead. Gate the compressed cache inode case on COMPRESS_CACHE, matching f2fs_init_compress_inode(). With compress_cache disabled, ino == max_nid now follows the normal inode path and is rejected as an out-of-range nid.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.13% probability · 3th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/0969926d987bbde9a1aa49da317582ba37095805
- https://git.kernel.org/stable/c/13e4b59d3a9413f66f116fa6c4828519b960a5ea
- https://git.kernel.org/stable/c/16161444c30d8dff9428abbae42b72ce4e32a932
- https://git.kernel.org/stable/c/29115b8c9172d34e67ab26cc4f6c209b7a236d7a
- https://git.kernel.org/stable/c/5073c66a96a9c23c0c2533ed4ed06e42f9021208
- https://git.kernel.org/stable/c/77f216ff9ce5cde8eed9f6d12707e906dffdc9f7
- https://git.kernel.org/stable/c/fcc051d377a9701a452e7663a1a8223c26225df9
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.