# CVE-2026-23465: btrfs: log new dentries when logging parent dir of a conflicting inode

> A logic error in the btrfs filesystem causes new directory entries to be lost after a power failure if specific fsync operations are performed.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Apr 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23465, DEBIAN-CVE-2026-23465, GHSA-wm46-26gp-9px3, ROOT-OS-DEBIAN-11-CVE-2026-23465, ROOT-OS-DEBIAN-12-CVE-2026-23465, ROOT-OS-UBUNTU-2204-CVE-2026-23465, ROOT-OS-UBUNTU-2404-CVE-2026-23465, UBUNTU-CVE-2026-23465

## What is CVE-2026-23465?

CVE-2026-23465 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Apr 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:

btrfs: log new dentries when logging parent dir of a conflicting inode

If we log the parent directory of a conflicting inode, we are not logging
the new dentries of the directory, so when we finish we have the parent
directory's inode marked as logged but we did not log its new dentries.
As a consequence if the parent directory is explicitly fsynced later and
it does not have any new changes since we logged it, the fsync is a no-op
and after a power failure the new dentries are missing.

Example scenario:

  $ mkdir foo

  $ sync

  $rmdir foo

  $ mkdir dir1
  $ mkdir dir2

  # A file with the same name and parent as the directory we just deleted
  # and was persisted in a past transaction. So the deleted directory's
  # inode is a conflicting inode of this new file's inode.
  $ touch foo

  $ ln foo dir2/link

  # The fsync on dir2 will log the parent directory (".") because the
  # conflicting inode (deleted directory) does not exists anymore, but it
  # it does not log its new dentries (dir1).
  $ xfs_io -c "fsync" dir2

  # This fsync on the parent directory is no-op, since the previous fsync
  # logged it (but without logging its new dentries).
  $ xfs_io -c "fsync" .

  <power failure>

  # After log replay dir1 is missing.

Fix this by ensuring we log new dir dentries whenever we log the parent
directory of a no longer existing conflicting inode.

A test case for fstests will follow soon.

## Which versions are affected by CVE-2026-23465?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23465?

Apply the vendor's patch.

## Is CVE-2026-23465 being exploited?

There is no known exploitation of CVE-2026-23465 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23465 and fix it if it is affected.

What it is: CVE-2026-23465 is a medium-severity denial of service vulnerability in Linux kernel, published on 3 Apr 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-2026-23465 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-23465/ (Markdown: https://insights.sbomify.com/CVE-2026-23465/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23465
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23465
- OSV: https://osv.dev/vulnerability/CVE-2026-23465

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23465/
Summaries are generated and may contain mistakes; the official description above is the record.