# CVE-2026-78501: Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability

> An attacker can exploit command injection in Microsoft 365 Copilot Business Chat to disclose sensitive information over the network.

- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Sep 2026
- **Updated:** 14 Oct 2026
- **Also known as:** GHSA-hjj2-64g6-jw5p

## What is CVE-2026-78501?

CVE-2026-78501 is a high-severity command injection vulnerability in Microsoft 365 Copilot's Business Chat, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Improper neutralization of special elements used in a command ('command injection') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to disclose information over a network.

Weakness: CWE-923 (Improper Restriction of Communication Channel to Intended Endpoints), CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2026-78501?

It affects 1 product.


Products: Microsoft 365 Copilot Chat.

## How do I fix CVE-2026-78501?

No fix has been published for CVE-2026-78501 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78501 being exploited?

There is no known exploitation of CVE-2026-78501 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft 365 Copilot's Business Chat

- [CVE-2026-26137](https://insights.sbomify.com/CVE-2026-26137/): Microsoft Exchange Elevation of Privilege Vulnerability (critical 9.9)
- [CVE-2025-59272](https://insights.sbomify.com/CVE-2025-59272/): Copilot Information Disclosure Vulnerability (critical 9.3)
- [CVE-2025-59286](https://insights.sbomify.com/CVE-2025-59286/): Copilot Information Disclosure Vulnerability (critical 9.3)
- [CVE-2025-53787](https://insights.sbomify.com/CVE-2025-53787/): Microsoft 365 Copilot BizChat Information Disclosure Vulnerability (high 8.2)
- [CVE-2026-26129](https://insights.sbomify.com/CVE-2026-26129/): M365 Copilot Information Disclosure Vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78501 and fix it if it is affected.

What it is: CVE-2026-78501 is a high-severity command injection vulnerability in Microsoft 365 Copilot's Business Chat, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-78501 in the wild and no public exploit code.

Affected product: Microsoft 365 Copilot's Business Chat. 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-2026-78501/ (Markdown: https://insights.sbomify.com/CVE-2026-78501/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78501
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78501
- OSV: https://osv.dev/vulnerability/CVE-2026-78501

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78501/
Summaries are generated and may contain mistakes; the official description above is the record.