# CVE-2026-74646: misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke

> A race condition in the Linux kernel fastrpc driver allows list corruption during interrupted invokes, potentially causing system crashes or denial of service.

- **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:** 22 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** BELL-CVE-2026-74646, DEBIAN-CVE-2026-74646, GHSA-487q-3fxv-jwrm, UBUNTU-CVE-2026-74646

## What is CVE-2026-74646?

CVE-2026-74646 is a high-severity 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:

misc: fastrpc: take fl->lock when moving mmaps on interrupted invoke

When an invoke is interrupted by a signal,
wait_for_completion_interruptible() returns -ERESTARTSYS and
fastrpc_internal_invoke() moves every buffer from fl->mmaps onto
cctx->invoke_interrupted_mmaps. This list_del()/list_add_tail() walk
runs without holding fl->lock, the lock that serialises fl->mmaps in
fastrpc_req_mmap() and fastrpc_req_munmap() everywhere else.

Take fl->lock around the move, matching every other fl->mmaps accessor.

## Which versions are affected by CVE-2026-74646?


## How do I fix CVE-2026-74646?

Apply the vendor's patch.

## Is CVE-2026-74646 being exploited?

There is no known exploitation of CVE-2026-74646 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74646 and fix it if it is affected.

What it is: CVE-2026-74646 is a high-severity 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-2026-74646 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-2026-74646/ (Markdown: https://insights.sbomify.com/CVE-2026-74646/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74646
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74646
- OSV: https://osv.dev/vulnerability/CVE-2026-74646

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74646/
Summaries are generated and may contain mistakes; the official description above is the record.