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CVE-2023-23376 is a privilege-escalation vulnerability in the Windows Common Log File System (CLFS) driver affecting Windows 10, Windows 11, and multiple Windows Server versions. Crafted Base Log File metadata exploits overlapping sector signatures and control-record offsets to substitute a malicious CLFS_CONTROL_RECORD after CClfsBaseFilePersisted::OpenImage has validated the original record. ExtendMetadataBlock does not independently validate the iExtendBlock and iFlushBlock indexes, allowing attacker-controlled indexes to select a sprayed memory pointer as a metadata-block pointer. Subsequent metadata processing provides an arbitrary memory-increment capability that can be developed into SYSTEM-level execution. Microsoft discovered active zero-day exploitation and patched the vulnerability in February 2023.
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What an attacker gets, and what they’ve been doing with it.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
10 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An earlier CLFS zero-day vulnerability referenced as having been used to deliver Nokoyawa ransomware.
A Microsoft vulnerability that CISA KEV’s knownRansomwareCampaignUse field silently flipped to Known during 2025 (evidence of ransomware campaign use).
A Windows Common Log File System (CLFS) privilege-escalation vulnerability used in ransomware attacks. A crafted BLF file exploits overlapping record-offset and sector-signature data to substitute a malicious CLFS_CONTROL_RECORD after initial validation. Unchecked block indexes then cause an attacker-controlled pointer to be used, enabling an arbitrary memory increment and subsequent privilege escalation. The described exploit uses PreviousMode corruption on supported systems or pipe-attribute corruption to build arbitrary read/write capabilities on newer Windows 11 builds.
An elevation-of-privilege vulnerability in the Microsoft Windows CLFS driver, exploited as a zero-day in ransomware attacks. The article identifies it as the fourth exploit examined in the accompanying research series and states that it has been patched.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.