CVE-2025-55234
An attacker who successfully exploited these vulnerabilities could perform relay attacks and make the users subject to elevation of privilege attacks.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 20.1%, higher than 97% of all known CVEs. Patch or mitigate before the next change window.
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 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 20.09% probability · 97th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287
- Affected
- microsoft/windows 10 1507 · microsoft/windows 10 1607 · microsoft/windows 10 1809 · microsoft/windows 10 21h2 · microsoft/windows 10 22h2 · microsoft/windows 11 22h2 · microsoft/windows 11 23h2 · microsoft/windows 11 24h2 · microsoft/windows server 2008 · microsoft/windows server 2012 · microsoft/windows server 2016 · microsoft/windows server 2019 · microsoft/windows server 2022 · microsoft/windows server 2022 23h2 · microsoft/windows server 2025
- Source
- secure@microsoft.com
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-55234Vendor Advisory
- https://www.vicarius.io/vsociety/posts/cve-2025-55234-detection-script-smb-server-vulnerability-affecting-microsoft-systems
- https://www.vicarius.io/vsociety/posts/cve-2025-55234-mitigation-script-smb-server-vulnerability-affecting-microsoft-systems
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.