Elevation of privilege via unsigned SMB authentication relay
Published Sep 9, 2025 · Updated Feb 26, 2026
Improper authentication in Microsoft Windows SMB Server allows remote attackers to elevate privileges by relaying a user's authentication. An SMB server that does not require signing or Extended Protection for Authentication accepts relayed authentication without binding it to the intended server. Exploitation requires user interaction, while required signing, EPA, or enforced SMB encryption blocks the relay.
Summary
What happened
Improper authentication in Microsoft Windows SMB Server allows remote attackers to elevate privileges by relaying a user's authentication. An SMB server that does not require signing or Extended Protection for Authentication accepts relayed authentication without binding it to the intended server. Exploitation requires user interaction, while required signing, EPA, or enforced SMB encryption blocks the relay.
The record
- CVE
- CVE-2025-55234
- Published
- Sep 9, 2025
- Updated
- Feb 26, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- CWE-287, T1557.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 9, 2025CVE publishedPublication date reported by the CVE source.
- Feb 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.10240.0 <10.0.10240.21128
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Impacket ntlmrelayx and smbrelayxfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo