Windows Cloud Files Mini Filter Driver Elevation of Privilege
CVE-2023-36036 is an elevation-of-privilege vulnerability in the Windows Cloud Files Mini Filter Driver (cldflt.sys). Microsoft describes it as a Windows Cloud Files Mini Filter Driver EoP flaw and reported it as actively exploited in the wild in November 2023. Supporting content ties this bug family to the cldflt.sys function HsmpRpiDecompressBuffer, the same function previously analyzed in detail for CVE-2021-31969. The available analysis indicates the CVE-2023-36036 patch added an upper bound check limiting the cstmDataSize field to 0x4000, implying the vulnerable path previously allowed an unchecked or insufficiently bounded size during decompression or buffer handling. Based on the provided context, exploitation involves crafted Cloud Files/reparse-related input reaching HsmpRpiDecompressBuffer and causing an out-of-bounds memory operation in kernel context, leading to local privilege escalation.
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Impact, mitigation & remediation
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Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A local privilege escalation vulnerability that the content says was used by Interlock and ModeloRAT operators.
A previously patched Windows Cloud Files Mini Filter Driver elevation-of-privilege vulnerability referenced as an example of a prior in-the-wild zero-day in the same component family.
A related vulnerability in the same cldflt.sys decompression path (HsmpRpiDecompressBuffer), patched later and described as actively exploited in the wild, apparently involving insufficient bounds checking on cstmDataSize.
An elevation-of-privilege vulnerability in the Windows Cloud Files Mini Filter Driver that can allow an attacker to escalate to SYSTEM privileges.
The version that knows your environment.
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.