# CVE-2026-72430: net/sched: act_ct: fix nf_connlabels leak on two error paths

> An unprivileged user with CAP_NET_ADMIN can leak kernel memory references via failed network actions, potentially causing resource exhaustion and denial of service.

- **Severity:** Not scored
- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72430, DEBIAN-CVE-2026-72430, GHSA-238f-h9q7-hg73, UBUNTU-CVE-2026-72430

## What is CVE-2026-72430?

CVE-2026-72430 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:

net/sched: act_ct: fix nf_connlabels leak on two error paths

tcf_ct_fill_params() calls nf_connlabels_get() (setting put_labels) when
TCA_CT_LABELS is present, but two later error sites use a bare return
instead of "goto err", skipping the err: nf_connlabels_put() cleanup.
They also precede the "p->put_labels = put_labels" assignment, so the
tcf_ct_params_free() fallback does not release the count either. Each
failed RTM_NEWACTION on these paths leaks one nf_connlabels reference:
net->ct.labels_used is incremented and never released. The action is
reachable with CAP_NET_ADMIN over the netns, i.e. from an unprivileged
user namespace on default-userns kernels.

Impact: an unprivileged user with CAP_NET_ADMIN over a network namespace
(e.g. via user namespaces) leaks one nf_connlabels reference per failed
RTM_NEWACTION on the two error paths; net->ct.labels_used is never
released.

The err: label is safe to reach from both sites: p->tmpl is still NULL
there (kzalloc'd, not yet assigned) and nf_ct_put(NULL) is a no-op, so
no inline release is needed.

## Which versions are affected by CVE-2026-72430?


## How do I fix CVE-2026-72430?

Apply the vendor's patch.

## Is CVE-2026-72430 being exploited?

There is no known exploitation of CVE-2026-72430 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72430 and fix it if it is affected.

What it is: CVE-2026-72430 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-2026-72430 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-2026-72430/ (Markdown: https://insights.sbomify.com/CVE-2026-72430/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72430
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72430
- OSV: https://osv.dev/vulnerability/CVE-2026-72430

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72430/
Summaries are generated and may contain mistakes; the official description above is the record.