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Microsoft Patches Exploited Exchange Server Vulnerability

SecurityWeekBy Eduard Kovacs

Reported exploitedExchange ServerOutlook Web Access

Our summary

Microsoft has released Patch Tuesday updates to address an Exchange Server vulnerability that is already being exploited in the wild, tracked as CVE-2026-42897. The flaw affects Exchange Server Subscription Edition, 2016, and 2019, and could be triggered via a specially crafted email leading to spoofing and cross-site scripting that allows JavaScript execution in a victim’s browser context. CISA added CVE-2026-42897 to its Known Exploited Vulnerabilities (KEV) catalog, requiring remediation by May 29, underscoring the urgency for organizations using affected Exchange deployments to apply the June 9 patches.

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  2. Help Net SecurityNearly 22,000 Microsoft Exchange servers remain exposed to critical security flaw (CVE-2026-62911)CVE-2026-42897
  3. BleepingComputerNearly 22,000 Microsoft Exchange servers vulnerable to hijack attacksCVE-2026-42897
  4. The Hacker News⚡ Weekly Recap: Rogue AI Models, $88M Bitcoin Theft, Water-System Attacks and Dangling DNS HijacksCVE-2026-42897
  5. Check Point Research3rd August – Threat Intelligence ReportCVE-2026-42897
  6. Help Net SecurityWeek in review: Claude breached three companies during tests, AD CS domain-takeover PoC releasedCVE-2026-42897
  7. Ars Technica (Security)Max-severity Exchange server flaw under active exploitation by Kremlin hackersCVE-2026-42897
  8. Help Net SecurityLaundry Bear’s new Microsoft Exchange attack triggers on email open (CVE-2026-42897)CVE-2026-42897
  9. The Hacker NewsRussian Hackers Exploit Microsoft OWA Flaw to Keep Mailbox Access After Credential RotationCVE-2026-42897
  10. BleepingComputerRussian hackers exploit Exchange OWA zero-day for long-term mailbox accessCVE-2026-42897

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