# CVE-2026-80983: net/smc: fix socket refcount leak in smc_switch_conns()

> A socket reference count leak in the Linux kernel SMC module can cause memory exhaustion and prevent network namespace teardown, leading to 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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100289, BELL-CVE-2026-80983, DEBIAN-CVE-2026-80983, GHSA-6pmg-4m98-jhww, UBUNTU-CVE-2026-80983

## What is CVE-2026-80983?

CVE-2026-80983 is a denial of service vulnerability in Linux, published on 11 Sep 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/smc: fix socket refcount leak in smc_switch_conns()

smc_switch_conns() takes a reference on the SMC socket before dropping
lgr->conns_lock, so the connection stays alive while the CDC slot is
fetched:

        sock_hold(&smc->sk);
        read_unlock_bh(&lgr->conns_lock);
        /* pre-fetch buffer outside of send_lock, might sleep */
        rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend);
        if (rc)
                goto err_out;

The err_out label only drops the wr_tx link reference, so this early exit
returns without the matching sock_put(). The second error exit is not
affected, because sock_put() has already run by then.

A leaked sk_refcnt means the smc_sock is never destroyed. Its send and
receive buffers stay allocated, and for a user socket the reference held
on the network namespace is never released, so the netns can no longer be
torn down.

smc_cdc_get_free_slot() fails when the target link goes down or when the
connection has been killed while the switch is in progress. Both are
reachable during the link failover this function implements, so the leak
is triggered by the same hardware events that make smc_switch_conns() run
in the first place.

Restructure so there is a single sock_put() covering both outcomes,
instead of adding a second one to the error path.

## Which versions are affected by CVE-2026-80983?


## How do I fix CVE-2026-80983?

Apply the vendor's patch.

## Is CVE-2026-80983 being exploited?

There is no known exploitation of CVE-2026-80983 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80983 and fix it if it is affected.

What it is: CVE-2026-80983 is a denial of service vulnerability in Linux, published on 11 Sep 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-2026-80983 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-2026-80983/ (Markdown: https://insights.sbomify.com/CVE-2026-80983/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80983
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80983
- OSV: https://osv.dev/vulnerability/CVE-2026-80983

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80983/
Summaries are generated and may contain mistakes; the official description above is the record.