SYSTEM privilege escalation via BLF size overflow
Published Aug 8, 2023 · Updated Aug 10, 2026
Integer overflow in the Windows Common Log File System driver allows local users to gain SYSTEM privileges through a crafted BLF file. CClfsBaseFilePersisted::ExtendMetadataBlockDescriptor rounds attacker-controlled metadata past 32 bits, allocates an undersized kernel buffer, and copies a larger block into it. A low-privileged local account can supply the malformed log file without user interaction; public research demonstrates a system crash, while Microsoft reports SYSTEM-level elevation.
Summary
What happened
Integer overflow in the Windows Common Log File System driver allows local users to gain SYSTEM privileges through a crafted BLF file. CClfsBaseFilePersisted::ExtendMetadataBlockDescriptor rounds attacker-controlled metadata past 32 bits, allocates an undersized kernel buffer, and copies a larger block into it. A low-privileged local account can supply the malformed log file without user interaction; public research demonstrates a system crash, while Microsoft reports SYSTEM-level elevation.
The record
- CVE
- CVE-2023-36900
- Published
- Aug 8, 2023
- Updated
- Aug 10, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- CWE-190, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 8, 2023CVE publishedPublication date reported by the CVE source.
- Aug 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.10240.0 <10.0.10240.20107
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
- CVE-2023-36900 denial-of-service proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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