NULL pointer dereference in Linux kernel - CVE-2026-63811
Published: July 21, 2026
Vulnerability identifier: #VU138835
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-2026-63811
CWE-ID: CWE-476
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 a null pointer dereference in f2fs atomic write handling when reading COW data during write-begin processing. A local user can update an atomic-write file in a crafted encryption-policy state to cause a denial of service.
The issue occurs when the original inode and its COW inode use different encryption contexts, causing decryption to be attempted on a folio owned by the original inode.
Affected software
Linux kernel
How to mitigate CVE-2026-63811
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3