Missing authorization in ScreenConnect client allows unauthorized file execution
CISA: ConnectWise ScreenConnect Improper Privilege Management and Missing Authorization Vulnerability
CVSS 3.1
9.9critical
EPSS
<1%p51
Published
()
KEV added
AI analysis
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).
What to 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.
Affected
ConnectWise ScreenConnect client (endpoint agent)
—
Estimated exposure
massplausibly millions of managed endpoints running the ScreenConnect client agent — ScreenConnect is a market-leading remote access/remote support platform whose client agent is broadly deployed across large downstream endpoint fleets by thousands of managed service providers, plausibly totaling millions of installations;…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
A condition in the ScreenConnect client may allow files to be transferred and executed through an active remote session without authorization or Host confirmation in certain circumstances. ScreenConnect servers are not impacted.
CISA Known Exploited Vulnerability
Affected
ConnectWise ScreenConnect
Required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
ConnectWise patched critical ScreenConnect flaw CVE-2026-84869 (CVSS 9.9) exploited since August 20 in worm-like attacks; CISA added it to KEV.
ConnectWise released urgent patches for CVE-2026-84869 (CVSS 9.9), a missing authorization and improper privilege management flaw in ScreenConnect allowing file transfer and execution through active remote sessions without host confirmation. Huntress reported in-the-wild exploitation since August 20, with attackers using rogue ScreenConnect clients to push four VBScript files for persistence and worm-like propagation to other ScreenConnect clients. The flaw is fixed in ScreenConnect 26.6.5, with disabling the TransferFiles permission as a temporary mitigation. CISA added the CVE to its KEV catalog, requiring federal agencies to patch within three days under BOD 26-04.
CISA added four actively exploited GitLab, JFrog Artifactory, and ConnectWise ScreenConnect flaws to the KEV catalog with imminent deadlines.
CISA added CVE-2026-42016 and CVE-2026-42018 (JFrog Artifactory), CVE-2026-84869 (ConnectWise ScreenConnect), and CVE-2026-85706 (GitLab, CVSS 10.0) to its KEV catalog. Artifactory flaws are being chained with CVE-2026-82329 in attacks observed August 15 to September 8, taking over self-hosted servers, creating persistent administrator accounts, and installing backdoors. ScreenConnect CVE-2026-84869 allows unauthorized file transfer and execution during remote sessions, linked by Huntress to malicious VBScript deliveries, and is fixed in version 26.6.5. GitLab's repository commits API path traversal exposes SSH keys, database credentials, deploy tokens, and CI/CD variables, with watchTowr already observing in-the-wild probes. Federal agencies must patch GitLab and ScreenConnect flaws by September 14, 2026, and Artifactory flaws by September 25, 2026.
CISA added five actively exploited JFrog Artifactory, ConnectWise ScreenConnect, and MikroTik RouterOS flaws to its KEV catalog.
CISA added five actively exploited vulnerabilities to the KEV catalog: CVE-2026-42016 and CVE-2026-42018 in JFrog Artifactory, CVE-2026-84869 in ConnectWise ScreenConnect (CVSS 9.9), and CVE-2026-67277 and CVE-2026-86060 in MikroTik RouterOS. The Artifactory bugs are chained with CVE-2026-82329 to gain administrative control, deploy malicious Groovy plugins, and install Rust-based backdoors. CERT Polska dubbed the RouterOS chain 'MikroTrick'; FCEB agencies must patch between September 13 and 25, 2026.
CISA added three actively exploited vulnerabilities — two JFrog Artifactory and one ConnectWise ScreenConnect — to its KEV Catalog.
CISA added CVE-2026-42016 (JFrog Artifactory incorrect authorization), CVE-2026-42018 (JFrog Artifactory improper authentication), and CVE-2026-84869 (ConnectWise ScreenConnect improper privilege management and missing authorization) to the Known Exploited Vulnerabilities Catalog based on evidence of active exploitation. BOD 26-04 requires Federal Civilian Executive Branch agencies to prioritize rapid remediation of such high-risk vulnerabilities on publicly exposed assets and to check for prior compromise. CISA urges all organizations to adopt risk-based vulnerability management and prioritize KEV remediation.
ConnectWise patches ScreenConnect CVE-2026-84869, reported exploited in the wild; administrators should update to 26.6.5.
ConnectWise shipped ScreenConnect 26.6.5 to fix a vulnerability tracked as CVE-2026-84869 affecting versions prior to 26.6.5. Open-source reporting indicates the flaw is being exploited in the wild. The Canadian Centre for Cyber Security issued advisory AV26-903 urging users and administrators to apply the patch.
ConnectWise patched ScreenConnect flaw CVE-2026-84869 five days after warning files could be transferred and executed via active sessions without authorization.
ConnectWise released ScreenConnect client version 26.6.5 and later to fix CVE-2026-84869, an authentication failure in ConnectWise Remote Access allowing unauthorized file transfer and execution through active remote sessions. The company warned customers on September 3 and advised admins to remove the TransferFiles permission from users with open sessions as an interim mitigation. The advisory does not state that exploitation has been observed.