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CVE-2026-24294 is an elevation-of-privilege vulnerability in Windows SMB Server caused by improper authentication handling during local NTLM reflection. The issue is associated with newer Windows support for SMB connections over arbitrary TCP ports, introduced in Windows 11 24H2 and Windows Server 2025. An attacker can establish a local SMB listener on a non-default port, induce the Windows SMB client to maintain a connection to that listener, and then coerce a privileged local service such as LSASS to authenticate to the same SMB path. Because the SMB client reuses the existing connection and the authentication is treated as local, the attacker can capture the privileged NTLM authentication and relay it to the host’s legitimate SMB service, obtaining a privileged SMB session. Public reporting indicates the technique can yield SYSTEM-level access on default Windows Server 2025 installations and was patched by Microsoft in March 2026.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
Repository contains a working exploit chain combining a modified Windows PetitPotam coercion client with a modified Impacket SMB server. The purpose is local NTLM reflection / privilege escalation on Windows Server 2025 by abusing SMB arbitrary-port connections plus SMB session multiplexing. The C++ project under PetitPotam/ is a Visual Studio solution that binds to the EFSRPC interface UUID df1941c5-fe89-4e79-bf10-463657acf44d over the named pipe \\pipe\\efsrpc using ncacn_np. It accepts three arguments: capture server, target server, and EFS API selector. It constructs a UNC path to \\<captureServer>\test\topotam.exe and invokes one of several EFSRPC methods (notably EfsRpcEncryptFileSrv in the README example) against the target. Success is inferred from expected RPC error codes such as ERROR_BAD_NETPATH or ERROR_ACCESS_DENIED, indicating the target attempted outbound access to the attacker-controlled UNC path. The generated files ms-efsrpc_c.c, ms-efsrpc_h.h, ms-dtyp.h, and ms-dtyp_h.h are MIDL-generated RPC client stubs and type definitions supporting the EFSRPC calls. They are not standalone exploit logic but provide the RPC interface implementation used by PetitPotam.cpp. The Python smbserver.py is a modified Impacket SMB server entry point. It adds a -relay-port option and hooks SMB2 SESSION_SETUP handling to capture a second NTLM authentication on an already-established multiplexed SMB connection, then forwards that authentication to a raw relay listener such as ntlmrelayx --raw-port. This turns the coerced authentication into a usable relay/reflection primitive. The README documents the full three-terminal workflow: start ntlmrelayx on raw port 6666 targeting smb://127.0.0.1, start smbserver.py on TCP 12345 with share name test and relay-port 6666, then mount \\127.0.0.1\test using /tcpport:12345 and run PetitPotam.exe 127.0.0.1 localhost 2. Expected outcome is command execution as NT AUTHORITY\SYSTEM. Overall, this is a real exploit repository, not merely detection code. It is operational rather than heavily weaponized: the coercion path/share is partly hardcoded, the workflow is manual, and it relies on external tooling (Impacket ntlmrelayx) for final command execution.
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30 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An NTLM reflection bypass vulnerability in Windows Server 2025 that can enable SYSTEM-level local compromise by abusing SMB over arbitrary TCP ports and relaying privileged local NTLM authentication.
A vulnerability arising from abuse of the new ability in Windows 11 24H2 and Windows Server 2025 to mount SMB shares on arbitrary TCP ports, enabling a demonstrated local privilege escalation attack path via localhost coercion.
A local privilege escalation vulnerability involving NTLM reflection via SMB arbitrary port connection reuse on recent Windows versions.
A local privilege escalation vulnerability on recent Windows versions that abuses SMB arbitrary-port connections and SMB connection reuse to relay local NTLM authentication back to the machine.
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