SYSTEM privilege escalation via malformed BLF metadata
Published Apr 11, 2023 · Updated Oct 21, 2025
Heap-based buffer overflow in the Windows CLFS driver allows local users with code execution to elevate privileges to SYSTEM. The CClfsBaseFilePersisted::ExtendMetadataBlock path trusts manipulated BLF metadata indexes, accesses the six-element m_rgBlocks array out of bounds, and passes the resulting pointer to WriteMetadataBlock for an increment. Exploitation requires authenticated user access and local code execution; successful corruption yields kernel read/write capability and SYSTEM privileges.
Summary
What happened
Heap-based buffer overflow in the Windows CLFS driver allows local users with code execution to elevate privileges to SYSTEM. The CClfsBaseFilePersisted::ExtendMetadataBlock path trusts manipulated BLF metadata indexes, accesses the six-element m_rgBlocks array out of bounds, and passes the resulting pointer to WriteMetadataBlock for an increment. Exploitation requires authenticated user access and local code execution; successful corruption yields kernel read/write capability and SYSTEM privileges.
The record
- CVE
- CVE-2023-28252
- Published
- Apr 11, 2023
- Updated
- Oct 21, 2025
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- CWE-122, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 1, 2023Exploitation reportedNokoyawa ransomware deployment attempts
- Apr 11, 2023CVE publishedPublication date reported by the CVE source.
- Oct 21, 2025Record 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 <10.0.10240.19869
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
- Fortra CVE-2023-28252 proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- Nokoyawa ransomware deployment attemptsransomware
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
Technologies
Your stack
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Your stack
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