# CVE-2026-50517: Microsoft M365 Copilot Remote Code Execution Vulnerability

> An authorized attacker can execute arbitrary code remotely via unsafe deserialization in Microsoft 365 Copilot.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **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:** 24 Jul 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-cfm3-7vpc-px47

## What is CVE-2026-50517?

CVE-2026-50517 is a critical unsafe deserialization vulnerability in Microsoft 365 Copilot, published on 24 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-50517?

It affects 1 product.


Products: Microsoft 365 Copilot.

## How do I fix CVE-2026-50517?

No fix has been published for CVE-2026-50517 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-50517 being exploited?

There is no known exploitation of CVE-2026-50517 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft 365 Copilot

- [CVE-2026-85885](https://insights.sbomify.com/CVE-2026-85885/): Microsoft 365 Copilot Elevation of Privilege Vulnerability (critical 9.9)
- [CVE-2026-54130](https://insights.sbomify.com/CVE-2026-54130/): M365 Copilot Information Disclosure Vulnerability (critical 9.8)
- [CVE-2025-60724](https://insights.sbomify.com/CVE-2025-60724/): GDI+ Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2025-53766](https://insights.sbomify.com/CVE-2025-53766/): GDI+ Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2026-48561](https://insights.sbomify.com/CVE-2026-48561/): Microsoft Edge Copilot Remote Code Execution Vulnerability (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50517 and fix it if it is affected.

What it is: CVE-2026-50517 is a critical unsafe deserialization vulnerability in Microsoft 365 Copilot, published on 24 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-50517 in the wild and no public exploit code.

Affected product: Microsoft 365 Copilot. 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-2026-50517/ (Markdown: https://insights.sbomify.com/CVE-2026-50517/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50517
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50517
- OSV: https://osv.dev/vulnerability/CVE-2026-50517

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50517/
Summaries are generated and may contain mistakes; the official description above is the record.