CVE-2025-55234
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 signingSMB 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 v3.1
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS v3.1
- 8.8 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - EPSS
- 20.09% chance of exploitation in the next 30 days, 97th percentile
- Published
- 2025-09-09
- Updated
- 2026-02-26
Proof-of-concept exploits (1)
- mrk336/CVE-2025-552340★ · 2025-09-13