# CVE-2026-98559: net/smc: fix UAF on lgr list traversal in smcr_port_err()

> A use-after-free vulnerability in the Linux kernel's SMC protocol allows attackers to cause denial of service or execute arbitrary code via concurrent list traversal.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109433, BELL-CVE-2026-98559, DEBIAN-CVE-2026-98559, GHSA-4x5q-83g5-68jv, UBUNTU-CVE-2026-98559

## What is CVE-2026-98559?

CVE-2026-98559 is an use after free vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix UAF on lgr list traversal in smcr_port_err()

smcr_port_err() traverses smc_lgr_list.list without holding
smc_lgr_list.lock, allowing a concurrent smc_lgr_terminate_sched()
to free an lgr while it is still being dereferenced.

Hold smc_lgr_list.lock across the traversal. Update
smc_ib_gid_check() to call smcr_port_err() after releasing the lock.

## Which versions are affected by CVE-2026-98559?


## How do I fix CVE-2026-98559?

Apply the vendor's patch.

## Is CVE-2026-98559 being exploited?

There is no known exploitation of CVE-2026-98559 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98559 and fix it if it is affected.

What it is: CVE-2026-98559 is an use after free vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98559 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-2026-98559/ (Markdown: https://insights.sbomify.com/CVE-2026-98559/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98559
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98559
- OSV: https://osv.dev/vulnerability/CVE-2026-98559

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98559/
Summaries are generated and may contain mistakes; the official description above is the record.