Out-of-bounds read in Linux kernel - CVE-2026-63818
Published: July 21, 2026
Vulnerability identifier: #VU138842
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63818
CWE-ID: CWE-125
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in f2fs_recover_orphan_inodes() when mounting a crafted f2fs image and replaying orphan inodes from the checkpoint pack. A local user can provide a crafted filesystem image with a corrupted orphan block entry count to cause a denial of service.
The issue occurs when the orphan block entry count is larger than F2FS_ORPHANS_PER_BLOCK, causing the recovery code to read past the ino[] array and interpret subsequent data as inode numbers.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-63818
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.96-1
linux (Debian package) - update to 6.12.96-1