CVE-2026-72159 ocfs2: reject non-inline dinodes with i_size and zero i_clusters
A malformed OCFS2 directory inode can cause a denial of service by forcing infinite loops during directory traversal when sparse allocation is disabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72159?
CVE-2026-72159 is a denial of service vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: reject non-inline dinodes with i_size and zero i_clusters
On a volume mounted without OCFS2_FEATURE_INCOMPAT_SPARSE_ALLOC, a non-inline regular file with non-zero i_size and zero i_clusters is structurally malformed: the extent map declares no allocated clusters yet the size header claims content exists. Keep rejecting that shape, but express it through a shared predicate so the same invariant is available to normal inode reads and online filecheck.
The same zero-cluster shape is also malformed for non-inline directories. ocfs2 directory growth allocates backing storage before advancing i_size, and ocfs2_dir_foreach_blk_el() later walks until ctx->pos reaches i_size_read(inode). A forged directory dinode with a huge i_size and no clusters would repeatedly fail on holes while advancing through the claimed size.
Sparse regular files remain exempt: on sparse-alloc volumes, truncate can legitimately grow i_size without allocating clusters. System inodes and inline-data dinodes also retain their separate storage rules.
Mirror the check in ocfs2_filecheck_validate_inode_block() as well. filecheck reports through its own error namespace, so malformed size/cluster state is logged as a filecheck invalid-inode result rather than via ocfs2_error(), but it must not proceed into ocfs2_populate_inode().
Which versions are affected by CVE-2026-72159?
How do I fix CVE-2026-72159?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-72159 being exploited?
There is no known exploitation of CVE-2026-72159 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72159, DEBIAN-CVE-2026-72159, GHSA-5wh8-rgp3-6j39, UBUNTU-CVE-2026-72159.