Out-of-bounds read in Linux kernel - CVE-2026-63796
Published: July 21, 2026
Vulnerability identifier: #VU138851
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-2026-63796
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 the ocfs2 group descriptor bitmap handling in fs/ocfs2/suballoc.c when processing a crafted group bitmap descriptor. A local user can provide a descriptor with oversized bg_size or bg_bits values to cause a denial of service.
Exploitation requires access to a malicious ocfs2 filesystem image or on-disk metadata.
Affected software
Linux kernel
How to mitigate CVE-2026-63796
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/296c6a42b1174395935ca4cfe8f393e37b698d54
- https://git.kernel.org/stable/c/336340a0f8a141df8a4eb21a5a86f8ffb87769f6
- https://git.kernel.org/stable/c/4cd57ebee395041099fcdfcabb00749ce38d8b27
- https://git.kernel.org/stable/c/8f9903b0cdbb3155a8899410330b4b4d583a7a5c
- https://git.kernel.org/stable/c/99c21e7263248c3f084756bfae08163cc5d6c62f
- https://git.kernel.org/stable/c/9bd541e09dffff27e5bec0f9f45b0228173a5375
- https://git.kernel.org/stable/c/c5a125eadba05ba421c4b55e68da22b4a40d32b4
- https://git.kernel.org/stable/c/d2cd59fa848f9f13796ef214d3b1b5ca9a3fe21e