# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72159, DEBIAN-CVE-2026-72159, GHSA-5wh8-rgp3-6j39, UBUNTU-CVE-2026-72159

## 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.

## Is CVE-2026-72159 being exploited?

There is no known exploitation of CVE-2026-72159 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72159 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-72159 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72159/ (Markdown: https://insights.sbomify.com/CVE-2026-72159/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72159
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72159
- OSV: https://osv.dev/vulnerability/CVE-2026-72159

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72159/
Summaries are generated and may contain mistakes; the official description above is the record.