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CVE-2026-42897 is an improper neutralization of input during web page generation vulnerability in the Outlook Web Access component of on-premises Microsoft Exchange Server. The flaw stems from insufficient sanitization of HTML content embedded in email messages when those messages are rendered in OWA, allowing attacker-controlled script content to execute in the victim's browser within the context of an authenticated OWA session. Exploitation is performed remotely by sending a specially crafted email to a target user; when the message is opened, and in some reporting previewed, in vulnerable OWA under the required interaction conditions, arbitrary JavaScript executes in the browser context. Affected products include on-premises Exchange Server Subscription Edition, Exchange Server 2016, and Exchange Server 2019, while Exchange Online is not affected. The vulnerability has been described by Microsoft as a spoofing issue, but the practical mechanism and observed abuse are browser-side cross-site scripting against OWA sessions.
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No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.
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339 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Microsoft Exchange Outlook Web Access (OWA) cross-site scripting vulnerability caused by inadequate HTML sanitization that allows malicious JavaScript to execute when a victim opens a crafted email in OWA, enabling deployment of the OWAReaper mailbox backdoor.
A Microsoft Exchange Server vulnerability listed among vulnerabilities actively exploited or operationally weaponized in July 2026.
A vulnerability exploited by TA488 to deploy the OWAReaper malware.
A maximum-severity cross-site scripting vulnerability in Microsoft Exchange Server / Outlook Web Access caused by improper filtering of HTML embedded in email, enabling malicious JavaScript execution and half-click compromise when a victim opens an email.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.