Microsoft Exchange Server Cross-Site Scripting Vulnerability

Microsoft Microsoft

Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context. Added to CISA KEV on 2026-05-15 (federal deadline 2026-05-29).

First seen: 15 May 2026
Last update: 15 May 2026, 12:00 UTC
Identifiers: CVE-2026-42897
Source: CISA KEV
On the menu as: Microsoft Office

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Microsoft Exchange Server Cross-Site Scripting Vulnerability
Severity: high, exploited in the wild. Patch status: patched.
Affected: Microsoft Microsoft
Ids: CVE-2026-42897

Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context. Added to CISA KEV on 2026-05-15 (federal deadline 2026-05-29).

## Steps
1. This touches infrastructure (office). Look in terraform, ansible, cloud-init, Dockerfiles and docs for the product and version we run. If it isn't in the repo, say so and list what a human should check on the box.

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-42897") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/security-best-practices/exchange-emergency-mitigation-service https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-42897 https://nvd.nist.gov/vuln/detail/CVE-2026-42897
https://pwned.coffee/i/microsoft-exchange-server-cross-site-scripting-vulnerabi-cve-2026-42897

Sources

Totalone hot coffee