# CVE-2026-6426: Qemu-kvm: vhost inflight migration vmstate integer type mismatch causes out-of-bounds access

> An integer type mismatch in QEMU's vhost inflight migration allows out-of-bounds writes, potentially causing crashes or code execution during VM migration.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 18 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-6426, ECHO-dd45-764e-65f0, GHSA-f3xx-69mr-6rx6, UBUNTU-CVE-2026-6426

## What is CVE-2026-6426?

CVE-2026-6426 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 10 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A type mismatch vulnerability was found in QEMU's vhost inflight migration VMState handling. The destination buffer size is stored as a uint64_t but read by the VMS_VBUFFER load path as a signed int32_t. On little-endian hosts, a crafted incoming migration state with bit 31 set causes the value to be interpreted as negative and then implicitly converted to a very large size_t, leading qemu_get_buffer() to copy migration-stream data beyond the bounds of the mmap-backed inflight region.

This can result in a crash of the QEMU process or memory corruption. Exploitation requires control of the migration producer or write access to the migration channel, combined with a destination configured to use vhost inflight migration.

Weakness: CWE-681 (Incorrect Conversion between Numeric Types)

## Which versions are affected by CVE-2026-6426?


## How do I fix CVE-2026-6426?

Apply the vendor's patch.

## Is CVE-2026-6426 being exploited?

There is no known exploitation of CVE-2026-6426 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6426 and fix it if it is affected.

What it is: CVE-2026-6426 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 10 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-6426 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2026-6426/ (Markdown: https://insights.sbomify.com/CVE-2026-6426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6426
- OSV: https://osv.dev/vulnerability/CVE-2026-6426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6426/
Summaries are generated and may contain mistakes; the official description above is the record.