Security2 hOctober 19, 2026, 18:00

CVE-2026-62911 in Exchange: replay-based authentication bypass

Microsoft Exchange Server has a CWE-294 capture-replay authentication bypass tracked as CVE-2026-62911 with a CVSS score of 8.0, patched on 11 August 2026. CSIRT.CZ reports roughly 22,000 internet-reachable unpatched Exchange servers and says a public exploit is available.

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CVE-2026-62911 in Exchange: replay-based authentication bypass

CVE-2026-62911 is a replay authentication bypass rated CVSS 8.0
Affects Exchange 2016 CU23, 2019 CU14/CU15 and Subscription Edition RTM
CSIRT.CZ: about 22,000 internet-facing Exchange servers unpatched
A public exploit is already available, CSIRT.CZ warns

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