# CVE-2026-57842: NetBSD COMPAT_NETBSD32 Double Free / Use-After-Free via recvmsg() msg_iovlen

> Local attackers can trigger kernel memory corruption or panic via recvmsg() in the COMPAT_NETBSD32 layer, potentially leading to code execution.

- **Severity:** High 7.3 (`CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **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:** No
- **Published:** 11 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-gq6w-h4cf-wpff

## What is CVE-2026-57842?

CVE-2026-57842 is a high-severity use after free vulnerability in The NetBSD Foundation NetBSD, 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

NetBSD contains a use-after-free and double-free vulnerability in msg_recv_copyin() within the COMPAT_NETBSD32 compatibility layer due to a missing return statement before the cleanup label on the success path. Any local user able to execute a 32-bit binary on a 64-bit NetBSD system can trigger a kernel panic or memory corruption by calling recvmsg() with msg_iovlen between 9 and IOV_MAX, causing the kernel to access a freed iovec buffer and subsequently free the same allocation a second time.

Weakness: CWE-416 (Use After Free), CWE-415 (Double Free)

## Which versions are affected by CVE-2026-57842?


## How do I fix CVE-2026-57842?

No fix has been published for CVE-2026-57842 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57842 being exploited?

There is no known exploitation of CVE-2026-57842 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57842 and fix it if it is affected.

What it is: CVE-2026-57842 is a high-severity use after free vulnerability in The NetBSD Foundation NetBSD, 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-2026-57842 in the wild and no public exploit code.

Affected product: The NetBSD Foundation NetBSD. 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-2026-57842/ (Markdown: https://insights.sbomify.com/CVE-2026-57842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57842
- OSV: https://osv.dev/vulnerability/CVE-2026-57842

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57842/
Summaries are generated and may contain mistakes; the official description above is the record.