# CVE-2026-26137: Microsoft Exchange Elevation of Privilege Vulnerability

> An authorized attacker can exploit Server-Side Request Forgery in Microsoft Exchange Online to elevate privileges over the network.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L/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:** 19 Mar 2026
- **Updated:** 19 Jun 2026
- **Also known as:** GHSA-88qf-p934-h9qg

## What is CVE-2026-26137?

CVE-2026-26137 is a critical server-side request forgery vulnerability in Microsoft Exchange Online, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Server-side request forgery (ssrf) in Microsoft Exchange allows an authorized attacker to elevate privileges over a network.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-26137?

It affects 1 product.


Products: Microsoft 365 Copilot Chat.

## How do I fix CVE-2026-26137?

No fix has been published for CVE-2026-26137 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-26137 being exploited?

There is no known exploitation of CVE-2026-26137 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Exchange Online

- [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-2026-78501](https://insights.sbomify.com/CVE-2026-78501/): Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability (high 8.6)
- [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-2026-26137 and fix it if it is affected.

What it is: CVE-2026-26137 is a critical server-side request forgery vulnerability in Microsoft Exchange Online, published on 19 Mar 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-2026-26137 in the wild and no public exploit code.

Affected product: Microsoft Exchange Online. 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-2026-26137/ (Markdown: https://insights.sbomify.com/CVE-2026-26137/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-26137
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26137
- OSV: https://osv.dev/vulnerability/CVE-2026-26137

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-26137/
Summaries are generated and may contain mistakes; the official description above is the record.