# CVE-2026-80979: net/smc: unregister the connection before draining the rx tasklet

> A use-after-free in the Linux kernel SMC subsystem allows attackers to cause denial of service or execute code via race conditions during connection teardown.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100082, BELL-CVE-2026-80979, DEBIAN-CVE-2026-80979, GHSA-3r27-v3q5-phcc, UBUNTU-CVE-2026-80979

## What is CVE-2026-80979?

CVE-2026-80979 is a high-severity use after free 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: unregister the connection before draining the rx tasklet

smc_conn_free() calls smc_ism_unset_conn() only while the link group is
still on its device list, and never sets conn->killed.
smc_lgr_terminate_sched() unlinks the group immediately and defers killing
its connections to a work item, so a connection freed in that window keeps
its smcd->conn[] slot with both gates in smcd_handle_irq() open, and the
device can re-arm the receive tasklet after tasklet_kill() has returned. On
the DMB-nocopy path the ghost send buffer is freed right after that drain,
so the re-armed tasklet dereferences it.

Unregister unconditionally and drain before the detach at both teardown
sites, mirroring rmb_desc, which smc_buf_unuse() releases after the drain.
Clear conn->sndbuf_desc before freeing it as well, so a reader that samples
the pointer cannot get one that is already freed.

## Which versions are affected by CVE-2026-80979?


## How do I fix CVE-2026-80979?

Apply the vendor's patch.

## Is CVE-2026-80979 being exploited?

There is no known exploitation of CVE-2026-80979 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80979 and fix it if it is affected.

What it is: CVE-2026-80979 is a high-severity use after free 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-2026-80979 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-2026-80979/ (Markdown: https://insights.sbomify.com/CVE-2026-80979/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80979
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80979
- OSV: https://osv.dev/vulnerability/CVE-2026-80979

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80979/
Summaries are generated and may contain mistakes; the official description above is the record.