# CVE-2026-46416: Microsoft UFO shared WebSocket handler state causes cross-client response hijacking

> An attacker can hijack WebSocket responses intended for other authenticated clients due to shared state in the Microsoft UFO framework.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 May 2026
- **Updated:** 28 May 2026

## What is CVE-2026-46416?

CVE-2026-46416 is a medium-severity vulnerability in microsoft UFO, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Microsoft UFO open-source framework for intelligent automation across devices and platforms. In 3.0.1-4-ge2626659, Microsoft UFO creates one shared UFOWebSocketHandler instance and reuses it for multiple authenticated WebSocket connections. The handler stores per-connection protocol objects in mutable instance fields. Each new WebSocket connection overwrites those fields. Later, message handlers send responses through the shared fields instead of through protocol objects bound to the originating connection. As a result, the most recently connected authenticated client can receive protocol responses that belong to another authenticated client.

Weakness: CWE-488 (Exposure of Data Element to Wrong Session), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-46416?


## How do I fix CVE-2026-46416?

No fix has been published for CVE-2026-46416 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-46416 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46416 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46416 and fix it if it is affected.

What it is: CVE-2026-46416 is a medium-severity vulnerability in microsoft UFO, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46416 exists.

Affected product: microsoft UFO. 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-2026-46416/ (Markdown: https://insights.sbomify.com/CVE-2026-46416/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46416
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46416
- OSV: https://osv.dev/vulnerability/CVE-2026-46416

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-46416/
Summaries are generated and may contain mistakes; the official description above is the record.