# CVE-2026-42897: Microsoft Exchange Server cross-site scripting in Outlook Web Access

Source: https://junglewise.ai/threats/cve-2026-42897-microsoft-exchange-server-cross-site-scripting-in-outlook-web  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-14. Updated: 2026-05-15  
License: CC BY 4.0 with a link back

CVE-2026-42897 · Severity: critical · CVSS 8.1 · Exploited in the wild · Published 2026-05-14

Microsoft Exchange Server, the widely used corporate email and calendaring platform, is vulnerable to a security flaw in its Outlook Web Access (OWA) component. An attacker can use this vulnerability to run malicious scripts in a user's web browser if the user interacts with a specially crafted link or page. This could allow an attacker to steal sensitive session information, impersonate users, or gain unauthorized access to corporate email accounts.

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

## Quick answers

**Is CVE-2026-42897 exploited in the wild?** Yes. CVE-2026-42897 is known to be exploited in the wild, first recorded on 15 May 2026. Treat it as urgent.

**How severe is CVE-2026-42897?** Critical severity, with a CVSS score of 8.1, published 14 May 2026.

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

**Is there a fix for CVE-2026-42897?** 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-2026-42897 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-42897?** Check whether you run Microsoft Exchange Server or Microsoft. 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

A Cross-Site Scripting (XSS) vulnerability exists in Microsoft Exchange Server due to improper neutralization of input during web page generation within Outlook Web Access (OWA). The vulnerability is classified as CWE-79 and allows an unauthenticated, remote attacker to execute arbitrary JavaScript in the context of a victim's browser. Exploitation requires a network-based attack vector and user interaction, such as clicking a malicious link. Successful exploitation can lead to session hijacking, unauthorized data access, and spoofing. This vulnerability has been reported as exploited in the wild.

## Affected products

- Microsoft Exchange Server

## Timeline

- 2026-05-14: disclosed
- 2026-05-15: advisory: NVD publication date
- 2026-05-15: exploited: Reported as exploited in the wild in advisory metadata.

## 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)