# CVE-2026-72307: mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()

> A refcount leak in the mlxsw driver allows local attackers to cause memory exhaustion and denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **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-2026-72307, DEBIAN-CVE-2026-72307, GHSA-7fcx-hvpg-5c9p, UBUNTU-CVE-2026-72307

## What is CVE-2026-72307?

CVE-2026-72307 is a memory corruption 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:

mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()

When mlxsw_sp_vrs_lpm_tree_replace() fails after replacing some VRs,
the error rollback loop does not correctly revert the preceding
replacements. The loop decrements the index but fails to update the
vr pointer, which still points to the VR that caused the failure. As
a result, the condition and the rollback call always operate on the
same VR, potentially calling mlxsw_sp_vr_lpm_tree_replace() multiple
times on it while never rolling back the earlier VRs. Those VRs
continue to hold a reference to new_tree acquired via
mlxsw_sp_lpm_tree_hold(), leaking the reference count of new_tree.

Fix by reinitializing vr inside the error loop with the updated index:

	vr = &mlxsw_sp->router->vrs[i];

so that the loop correctly iterates over all VRs that were actually
replaced.

## Which versions are affected by CVE-2026-72307?


## How do I fix CVE-2026-72307?

Apply the vendor's patch.

## Is CVE-2026-72307 being exploited?

There is no known exploitation of CVE-2026-72307 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72307 and fix it if it is affected.

What it is: CVE-2026-72307 is a memory corruption 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-2026-72307 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-2026-72307/ (Markdown: https://insights.sbomify.com/CVE-2026-72307/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72307
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72307
- OSV: https://osv.dev/vulnerability/CVE-2026-72307

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72307/
Summaries are generated and may contain mistakes; the official description above is the record.