CVE Catalog

CVE-2026-63818

HighCVSS 8.4
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.14%

4th percentile - higher than 4% of all known CVEs

Summary

In the Linux kernel's F2FS filesystem, the orphan inode recovery function trusts the entry_count from the checkpoint block. A corrupted value larger than F2FS_ORPHANS_PER_BLOCK causes an out-of-bounds read and interprets subsequent data as inode numbers, leading to a kernel panic.

Risk Assessment

An attacker can use a crafted filesystem image to cause a kernel panic during mount, resulting in service disruption.

Recommendation

Apply the Linux kernel patch that validates entry_count before processing, so mounting fails with -EFSCORRUPTED and forces fsck.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS