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.
- 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
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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-72430 being exploited?
There is no known exploitation of CVE-2026-72430 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72430, DEBIAN-CVE-2026-72430, GHSA-238f-h9q7-hg73, UBUNTU-CVE-2026-72430.