# CVE-2026-72006: net/mlx5: free mlx5_st_idx_data on final dealloc

> A memory leak in the Linux kernel mlx5 driver allows attackers to cause denial of service by exhausting kernel memory through repeated RDMA operations.

- **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-2026-72006, DEBIAN-CVE-2026-72006, GHSA-x8q3-8m8p-mx7v, UBUNTU-CVE-2026-72006

## What is CVE-2026-72006?

CVE-2026-72006 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:

net/mlx5: free mlx5_st_idx_data on final dealloc

Workloads that repeatedly allocate and release mkeys carrying TPH
steering-tag hints (e.g. churning RDMA MRs) leak one
struct mlx5_st_idx_data per cycle; kmemleak flags it as unreferenced
and the kmalloc slab grows over time.

When the last reference to an ST table entry is dropped,
mlx5_st_dealloc_index() removed the entry from idx_xa but the backing
mlx5_st_idx_data allocation was never freed.

Free idx_data after the xa_erase() so the lifetime of the bookkeeping
struct matches the lifetime of the ST entry it tracks.

## Which versions are affected by CVE-2026-72006?


## How do I fix CVE-2026-72006?

Apply the vendor's patch.

## Is CVE-2026-72006 being exploited?

There is no known exploitation of CVE-2026-72006 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72006 and fix it if it is affected.

What it is: CVE-2026-72006 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-2026-72006 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-2026-72006/ (Markdown: https://insights.sbomify.com/CVE-2026-72006/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72006
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72006
- OSV: https://osv.dev/vulnerability/CVE-2026-72006

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72006/
Summaries are generated and may contain mistakes; the official description above is the record.