CVE-2026-63818

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

f2fs: validate orphan inode entry count

f2fs_recover_orphan_inodes() trusts the orphan block entry_count when

replaying orphan inodes from the checkpoint pack. A corrupted entry_count

larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the

ino[] array and interpret footer or following data as inode numbers.

On a crafted image, mounting an unpatched kernel can drive orphan recovery

into f2fs_bug_on() and panic the kernel. Validate entry_count before

consuming entries so corrupted checkpoint data fails the mount with

-EFSCORRUPTED and requests fsck instead.

Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be

recorded in the superblock s_errors[] field. This gives fsck a persistent

hint even though mount-time orphan recovery failure may leave no chance to

persist SBI_NEED_FSCK through a checkpoint.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References