# CVE-2026-118207: Microsoft Exchange Server improper input validation code execution

Source: https://junglewise.ai/threats/cve-2026-118207-improper-input-validation-in-microsoft-exchange-server-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-118207 · Severity: high · CVSS 8.8 · Published 2026-11-10

Microsoft Exchange Server, which handles corporate email and collaboration, contains a flaw that allows authorized users to run arbitrary code on the mail server over the network. An attacker with valid credentials could gain control of the server and access to all email and data passing through it.

Technologies: [Microsoft Exchange Server](https://junglewise.ai/threats/technologies/exchange-server). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-118207 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118207 being exploited in the wild.

**How severe is CVE-2026-118207?** High severity, with a CVSS score of 8.8, published 10 November 2026.

**Which products and versions are affected?** Microsoft Exchange Server.

**Is there a fix for CVE-2026-118207?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-118207 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-118207?** Check whether you run Microsoft Exchange Server. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

Improper input validation in Exchange Server enables authenticated remote code execution. An authorized attacker can exploit this flaw by sending specially crafted input over the network to execute arbitrary code with Exchange Server privileges, compromising confidentiality and integrity of the entire messaging system.

## Affected products

- Microsoft Exchange Server

## Timeline

- 2026-11-10: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118207](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118207)

## Related threats

- [Microsoft Exchange Server improper access control spoofing](https://junglewise.ai/threats/cve-2026-118208-improper-access-control-in-microsoft-exchange-server-allows-an)
- [Microsoft Exchange Server weak authentication privilege elevation](https://junglewise.ai/threats/cve-2026-118157-weak-authentication-in-microsoft-exchange-server-allows-an)
- [Microsoft Exchange Server privilege elevation via untrusted security decision input](https://junglewise.ai/threats/cve-2026-118154-reliance-on-untrusted-inputs-in-a-security-decision-in-microsoft)
- [Microsoft Exchange Server algorithmic complexity denial of service](https://junglewise.ai/threats/cve-2026-118153-inefficient-algorithmic-complexity-in-microsoft-exchange-server)
- [Microsoft Exchange Server CSRF spoofing](https://junglewise.ai/threats/cve-2026-118152-cross-site-request-forgery-csrf-in-microsoft-exchange-server)