The Server Message Block (SMB) driver (MRXSMB.SYS) in Microsoft Windows 2000 SP4, XP SP1 and SP2, and Server 2003 SP1 and earlier allows local users to cause a denial of service (hang) by calling the MrxSmbCscIoctlCloseForCopyChunk with the file handle of the shadow device, which results in a deadlock, aka the "SMB Invalid Handle Vulnerability."
Severity
CVSS 3.1
5.5 medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS
1.7% chance of exploitation in the next 30 days; higher than 77% of CVEs (scores of 2026-10-31)