CVE-2026-55008: Microsoft Exchange Server Spoofing Vulnerability
This Microsoft advisory covers CVE-2026-55008 in Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 14 and Microsoft Exchange Server 2019 Cumulative Update 15.
- CVE-2026-55008
Key facts
- Vendor rating
- Critical, CVSS 9.6
- CISA KEV
- Not listed (catalogue checked )
- Affected
- Microsoft Exchange Server 2016 Cumulative Update 23 15.01.0.0; Microsoft Exchange Server 2019 Cumulative Update 14 15.02.0.0; Microsoft Exchange Server 2019 Cumulative Update 15 15.02.0.0 and 1 more below
- Fixed in
- KB5103215 (build 15.01.2507.071), KB5103214 (build 15.02.1544.043), KB5103213 (build 15.02.1748.048) and 1 more below
- Source published
- Source revised
- Listed by VulniPulse
Compiled by VulniPulse from the linked sources. How records are collected and checked.
Affected products & platforms
Description
Microsoft Exchange Server Spoofing Vulnerability
Affected products named by the advisory: Microsoft Exchange Server 2016 Cumulative Update 23; Microsoft Exchange Server 2019 Cumulative Update 14; Microsoft Exchange Server 2019 Cumulative Update 15; Microsoft Exchange Server Subscription Edition RTM.
Text from the source record.
- Microsoft Exchange Server 2016 Cumulative Update 23 15.01.0.0
- Microsoft Exchange Server 2019 Cumulative Update 14 15.02.0.0
- Microsoft Exchange Server 2019 Cumulative Update 15 15.02.0.0
- Microsoft Exchange Server Subscription Edition RTM 15.02.0.0
Official advisory · high-confidence parse· fetched ·verify at source
How to fix CVE-2026-55008
Upgrade to a fixed release named by Microsoft:
- KB5103215 (build 15.01.2507.071)
- KB5103214 (build 15.02.1544.043)
- KB5103213 (build 15.02.1748.048)
- KB5103212 (build 15.02.2562.045)
Vendor guidance
- Install the applicable security update for your platform: KB5103215, KB5103214, KB5103213, KB5103212 (see the Microsoft Update Catalog).
End-of-life dates for Microsoft Exchange Server
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Microsoft Server advisories, July 2026All Microsoft Server advisories
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