Critical severity · published Jul 14, 2026
CVE-2026-55008
Microsoft Exchange Server Spoofing Vulnerability
9.6
CVSS
0.9%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.9% · higher than 58% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ES
Exchange Server · Microsoft
2016; 2019; 2019 · source: NVD
ME
Microsoft Exchange Server 2016 Cumulative Update 23 · Microsoft
15.01.0.0 before 15.01.2507.071 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 14 · Microsoft
15.02.0.0 before 15.02.1544.043 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 15 · Microsoft
15.02.0.0 before 15.02.1748.048 · source: vendor
ME
Microsoft Exchange Server Subscription Edition RTM · Microsoft
15.02.0.0 before 15.02.2562.045 · source: vendor
ES
Exchange Server Subscription Edition · Microsoft
before 15.02.2562.045 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55008
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55008
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55008
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