# CVE-2026-74631: net: smc: fix splice entry lifetime imbalance in smc_rx_splice

> A refcount imbalance in the Linux kernel SMC network module allows attackers to trigger a use-after-free, potentially leading to code execution or privilege escalation.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 22 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97118, BELL-CVE-2026-74631, DEBIAN-CVE-2026-74631, GHSA-75cj-q634-phhq, UBUNTU-CVE-2026-74631

## What is CVE-2026-74631?

CVE-2026-74631 is a high-severity use after free vulnerability in Linux, published on 22 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: smc: fix splice entry lifetime imbalance in smc_rx_splice

smc_rx_splice() passes pages to splice_to_pipe() before taking the
references that cover the lifetime of each splice entry. In the
VM-backed RMB path, splice_to_pipe() may drop unqueued entries through
smc_rx_spd_release(), while queued entries are released later via the
pipe buffer callback.

The old post-splice accounting also derives the number of queued VM pages
from an offset mutated while building the descriptor, and a multi-page
splice pairs one sock_hold() with multiple sock_put() calls.

Take the page and socket references for every candidate entry before
splice_to_pipe(), and drop the matching private state, page reference,
and socket reference from smc_rx_spd_release() for entries that never
get queued. This fixes a refcount imbalance that can underflow page
refcounts and trigger a use-after-free.

## Which versions are affected by CVE-2026-74631?


## How do I fix CVE-2026-74631?

Apply the vendor's patch.

## Is CVE-2026-74631 being exploited?

There is no known exploitation of CVE-2026-74631 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74631 and fix it if it is affected.

What it is: CVE-2026-74631 is a high-severity use after free vulnerability in Linux, published on 22 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-2026-74631 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-2026-74631/ (Markdown: https://insights.sbomify.com/CVE-2026-74631/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74631
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74631
- OSV: https://osv.dev/vulnerability/CVE-2026-74631

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74631/
Summaries are generated and may contain mistakes; the official description above is the record.