ConnectWise patches critical ScreenConnect authentication failure after five days

CVE-2026-84869 is a critical authorization flaw (CWE-862 missing authorization, CWE-269 improper privilege management) in the ScreenConnect client, the endpoint-side agent of ConnectWise's widely used remote access and remote support platform, in which files can be transferred to a machine and executed during an active remote session without the expected authorization or without confirmation by the Host (technician). It is triggered in certain circumstances during an active session, with a network attack vector, low attack complexity, low privileges required, and no user interaction per the CVSS 3.1 vector. An actor who obtains or already holds access to a session context could thereby push and run files on the managed endpoint, potentially achieving code execution with high confidentiality, integrity, and availability impact (CVSS 3.1 score 9.9, scope changed). Only endpoints running the ScreenConnect client are affected; ScreenConnect servers are not impacted, and the affected client version ranges are governed by ConnectWise security advisory AV26-903 (not enumerated in the available data). The flaw is not currently known to be exploited: it is not in CISA KEV, no public proof of concept is known, and EPSS assigns a modest 0.4% probability of exploitation within the next 30 days (32nd percentile).

Do: Follow ConnectWise security advisory AV26-903 and update ScreenConnect clients to the patched version it specifies, noting that ScreenConnect servers do not require remediation. Until patching is complete, monitor active remote sessions, require Host confirmation for file transfers, and review recent sessions on high-value endpoints for unexpected transferred or executed files; given no known exploitation and the active-session prerequisite, prioritize endpoints routinely accessed remotely.