# CVE-2026-69356: Microsoft Exchange Server cross-site scripting in web page generation

Source: https://junglewise.ai/threats/cve-2026-69356-microsoft-exchange-server-cross-site-scripting-in-web-page  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-69356 · Severity: critical · CVSS 9.3 · Published 2026-09-08

Microsoft Exchange Server is a widely-deployed enterprise email and collaboration platform. A cross-site scripting (XSS) vulnerability in the web interface allows an attacker to inject malicious scripts that execute in users' browsers, potentially leading to session hijacking, credential theft, or email tampering without requiring special privileges.

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

## Quick answers

**Is CVE-2026-69356 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-69356 being exploited in the wild.

**How severe is CVE-2026-69356?** Critical severity, with a CVSS score of 9.3, published 8 September 2026.

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

**Is there a fix for CVE-2026-69356?** 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-2026-69356 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-69356?** 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

This is an improper input neutralization vulnerability (CWE-79, cross-site scripting) in Microsoft Exchange Server's web page generation. The vulnerability allows an unauthorized attacker to inject arbitrary script code that runs in the context of a user's browser session, enabling spoofing attacks. The attack vector is network-based and does not require prior authentication or user interaction beyond normal web browsing. An attacker can exploit this to perform credential harvesting, session hijacking, or malware distribution via the Exchange web interface. Patches are available from Microsoft Security Response Center.

## Affected products

- Microsoft Exchange Server

## Timeline

- 2026-09-08: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69356](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69356)

## 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 improper input validation code execution](https://junglewise.ai/threats/cve-2026-118207-improper-input-validation-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)