# CVE-2026-68450: btrfs: free mapping node on duplicate reloc root insert

> A memory leak in the Linux kernel btrfs filesystem occurs when a duplicate reloc root insert fails, potentially leading to resource exhaustion and denial of service.

- **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:** 12 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-68450, DEBIAN-CVE-2026-68450, GHSA-mmwm-g85r-pjj6, UBUNTU-CVE-2026-68450

## What is CVE-2026-68450?

CVE-2026-68450 is a memory corruption vulnerability in Linux, published on 12 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:

btrfs: free mapping node on duplicate reloc root insert

__add_reloc_root() allocates a mapping_node before inserting it into
rc->reloc_root_tree.  If rb_simple_insert() finds an existing entry, it
returns the existing rb_node and leaves the newly allocated node unlinked.

The error path then returns -EEXIST without freeing the new node.  Since
the node was never inserted into reloc_root_tree, the later cleanup in
put_reloc_control() cannot find it either.

Free the newly allocated node before returning -EEXIST.

The callers currently assert that -EEXIST should not happen, so this is a
defensive cleanup for an unexpected duplicate insert path.  If the path is
ever reached, the local allocation should still be released.

## Which versions are affected by CVE-2026-68450?


## How do I fix CVE-2026-68450?

Apply the vendor's patch.

## Is CVE-2026-68450 being exploited?

There is no known exploitation of CVE-2026-68450 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68450 and fix it if it is affected.

What it is: CVE-2026-68450 is a memory corruption vulnerability in Linux, published on 12 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-2026-68450 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-2026-68450/ (Markdown: https://insights.sbomify.com/CVE-2026-68450/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68450
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68450
- OSV: https://osv.dev/vulnerability/CVE-2026-68450

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68450/
Summaries are generated and may contain mistakes; the official description above is the record.