---
id: "CVE-2026-42897"
kind: "vulnerability"
aliases: ["CVE-2026-42897"]
title: "Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server\u2026"
severity: "high"
cvss: 8.1
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "Microsoft Microsoft", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft exchange server", "fixed": [], "affected": "= 2016", "ecosystem": "vendor"}, {"name": "microsoft exchange server", "fixed": [], "affected": "= 2019", "ecosystem": "vendor"}, {"name": "microsoft exchange server subscription edition", "fixed": ["15.02.2562.043"], "affected": "< 15.02.2562.043", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exchange-server", "exploited", "on-premises-exchange", "outlook-web-access", "vendor"]
not_affected_if: ["exchange-online"]
published_at: "2026-05-14T18:16:49+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-42897", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42897", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server…

Microsoft Exchange Server has a cross-site scripting flaw in Outlook Web Access: when certain interaction conditions are met, an attacker can get arbitrary JavaScript to run in a user's browser session. CISA lists it as actively exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Microsoft affected ? fixed ?
- vendor:microsoft exchange server affected = 2016 fixed ?
- vendor:microsoft exchange server affected = 2019 fixed ?
- vendor:microsoft exchange server subscription edition affected < 15.02.2562.043 fixed 15.02.2562.043

## Fix

Apply the mitigations in Microsoft's vendor advisory for CVE-2026-42897; the sources do not name the patched build. If no mitigation is available, CISA says to discontinue use of the product.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-42897
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-42897

## From the sources

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.

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_