High [CVE-2026-42897] Microsoft Exchange Server Spoofing Vulnerability
This high-severity Microsoft Server advisory covers CVE-2026-42897 affecting Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 14, Microsoft Exchange Server 2019 Cumulative Update 15.
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Summary
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
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.
CISA Known Exploited Vulnerability
- Listed:
- May 15, 2026 · federal remediation due May 29, 2026
- 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.
- Ransomware use:
- Unknown
KEV is a prioritization signal from CISA — remediation detail still comes from the vendor advisory.
- Microsoft Exchange Server 2016 Cumulative Update 23 15.01.0.0 before 15.01.2507.069
- Microsoft Exchange Server 2019 Cumulative Update 14 15.02.0.0 before 15.02.1544.041
- Microsoft Exchange Server 2019 Cumulative Update 15 15.02.0.0 before 15.02.1748.046
- Microsoft Exchange Server Subscription Edition RTM 15.02.0.0 before 15.02.2562.043
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
- 15.01.2507.069
- 15.02.1544.041
- 15.02.1748.046
- 15.02.2562.043
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation
Upgrade to a fixed release: 15.01.2507.069, 15.02.1544.041, 15.02.1748.046, 15.02.2562.043. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Discussion(0)
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