Critical severity · published Sep 9, 2025
CVE-2025-55234
SMB Server might be susceptible to relay attacks depending on the configuration
9.8
CVSS
20.6%
EPSS
No
On KEV
Description
SMB Server might be susceptible to relay attacks depending on the configuration. An attacker who successfully exploited these vulnerabilities could perform relay attacks and make the users subject to elevation of privilege attacks. The SMB Server already supports mechanisms for hardening against relay attacks: SMB Server signing SMB Server Extended Protection for Authentication (EPA) Microsoft is releasing this CVE to provide customers with audit capabilities to help them to assess their environment and to identify any potential device or software incompatibility issues before deploying SMB Server hardening measures that protect against relay attacks. If you have not already enabled SMB Server hardening measures, we advise customers to take the following actions to be protected from these relay attacks: Assess your environment by utilizing the audit capabilities that we are exposing in the September 2025 security updates. See Support for Audit Events to deploy SMB Server Hardening—SMB Server Signing & SMB Server EPA. Adopt appropriate SMB Server hardening measures.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)20.6% · higher than 98% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
W1
Windows 10 1507 · Microsoft
before 10.0.10240.21128; before 10.0.10240.21128 · source: NVD
W1
Windows 10 1607 · Microsoft
before 10.0.14393.8422; before 10.0.14393.8422 · source: NVD
W1
Windows 10 1809 · Microsoft
before 10.0.17763.7792; before 10.0.17763.7792 · source: NVD
W1
Windows 10 21h2 · Microsoft
before 10.0.19044.6332 · source: NVD
W1
Windows 10 22h2 · Microsoft
before 10.0.19045.6332 · source: NVD
W1
Windows 11 22h2 · Microsoft
before 10.0.22621.5909 · source: NVD
W1
Windows 11 23h2 · Microsoft
before 10.0.22631.5909 · source: NVD
W1
Windows 11 24h2 · Microsoft
before 10.0.26100.6508 · source: NVD
WS
Windows Server 2016 · Microsoft
before 10.0.14393.8422 · source: NVD
WS
Windows Server 2019 · Microsoft
before 10.0.17763.7792 · source: NVD