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. 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.
Affected versions
Linux kernel versions
5.13.19,
5.14
and later are affected. Fixed in
6.1.177,
6.6.144,
6.12.95,
6.18.38,
7.1.3,
7.2-rc1
and their respective stable series.
References
6 totalFrequently asked questions
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What is CVE-2026-63817?
CVE-2026-63817 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.13.19 onward and has been patched in 6.1.177, 6.6.144, 6.12.95 and others. CVE-2026-63817 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-63817?
Yes — CVE-2026-63817 has been patched. Fixed versions include 6.1.177, 6.6.144, 6.12.95 and others. If you are running Linux kernel 5.13.19 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-63817 actively exploited?
No — CVE-2026-63817 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.