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ConnectWise

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ConnectWise patches critical ScreenConnect authentication failure after five days

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.

CSO Onlineupdated · 1d agofirst · 4d agoVulnerability 3 sourcesCVE-2026-84869

Modified ScreenConnect Clients Used in Worm-Like Campaign

Huntress warns of worm-like attacks using modified ScreenConnect clients to spread VBScript payloads; ConnectWise issued an advisory.

Campaigns starting in late August use social engineering, including Quick Assist abuse, to install rogue ScreenConnect clients that spawn wscript.exe and deploy four VBScript files for reconnaissance, staging, and PowerShell execution. The attackers persist via User Run Keys, attempt UAC bypass, install UltraViewer, and propagate the VBScript chain to other connected ScreenConnect endpoints. ConnectWise published an advisory about a file transfer behavior issue affecting cloud and on-premises ScreenConnect, with a CVE identifier and fix expected within a week; it recommends disabling file transfer meanwhile.

SecurityWeek · 8d agoExploit / PoC in the wild

Rogue ScreenConnect Clients Spread Four-Stage VBScript Chain to Newly Connected Hosts

Huntress says rogue ScreenConnect clients spread a four-stage VBScript chain delivering backdoors, privilege-escalation tools, or an XMRig miner to newly connected hosts.

Huntress identified three unrelated August 2026 incidents using a Quick Assist tech-support scam, a phishing-delivered MSI installer, and a fake Geek Squad refund form to install rogue ScreenConnect clients. Each client repeatedly spawned wscript.exe to run 1.vbs through 4.vbs, which profiled the host, enumerated installed security products, and downloaded stage-specific payloads from Dropbox. Depending on detected state, payloads included a user-level ScreenConnect backdoor, UAC-bypass privilege escalation tooling, or tunneling utilities with an XMRig cryptocurrency miner. Infected clients re-infected newly connected hosts, creating worm-like propagation, and ConnectWise issued an advisory about affected file transfer behavior in ScreenConnect.

The Hacker News · 8d agoMalware in the wild

ConnectWise warns of new ScreenConnect flaw without patch

ConnectWise warns of an unpatched ScreenConnect flaw affecting file transfer in support sessions and shares interim mitigations for MSPs.

ConnectWise disclosed a new ScreenConnect Remote Access vulnerability affecting file transfer behavior in both cloud and on-premises deployments; no CVE ID or patch is available yet, with a fix planned later this week. The vendor published temporary mitigation steps that remove TransferFiles permissions from session groups across all roles. Shadowserver tracks nearly 6,000 internet-exposed ScreenConnect instances. Previous ScreenConnect flaws, including CVE-2024-1709, were exploited by ransomware gangs and North Korea's Kimsuky, and three ScreenConnect vulnerabilities are on CISA's actively exploited catalog.

Rogue ScreenConnect Installations Across Unrelated Hosts Suggest Worm-Like Activity

Huntress observed rogue ScreenConnect deployments with worm-like VBScript propagation across unrelated organizations, prompting a ConnectWise advisory on file transfer behavior.

Huntress identified multiple incidents in late August 2026 where social engineering led to rogue ScreenConnect remote access clients deployed on victim machines, which then spawned wscript.exe to run four VBScript payloads (1.vbs through 4.vbs) for profiling, telemetry collection, and persistence via a WindowsServiceHost Run key. Modified ScreenConnect clients propagated the VBScript chain to connected endpoints, creating worm-like spread. ConnectWise published an advisory on September 3, 2026, confirming an issue affecting file transfer behavior in both cloud and on-premises ScreenConnect deployments, with a CVE and fix expected within the week; partners were advised to review and disable TransferFiles permissions in the interim.

Huntress · 12d agoExploit / PoC in the wild

Related CVEs

  • Authentication Bypass in ConnectWise ScreenConnect Creates Rogue Admin Accounts
    ConnectWise ScreenConnect (ConnectWise Control), a widely used remote-access and remote-monitoring tool, contains an authentication bypass (CWE-288) in its management interface. An attacker needs only network access to the management interface to trigger the flaw, with no valid credentials or user interaction required. A successful attacker gains administrative control of the ScreenConnect server by creating a new administrator-level account, providing a foothold that has already been used in ransomware campaigns against downstream managed environments. Any organization running ConnectWise ScreenConnect is affected, especially managed service providers and IT teams whose management interface is reachable from the internet; the source data specifies affected products but no version ranges. Exploitation is confirmed and urgent: CISA added the flaw to the KEV on 2024-02-22 with known ransomware use, EPSS assigns a 100% probability of exploitation within 30 days, and ConnectWise warned that no patch was available at the time of disclosure.
    · ConnectWise ScreenConnect KEV ransomware PoC ×3mass
  • Missing authorization in ScreenConnect client allows unauthorized file execution
    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).
    · ConnectWise ScreenConnect client (endpoint agent) KEVmass
  • ViewState Code Injection in ConnectWise ScreenConnect May Lead to RCE
    ConnectWise ScreenConnect versions 25.2.3 and earlier rely on ASP.NET Web Forms ViewState, whose integrity depends on machine keys; if an attacker with privileged system-level access obtains those keys, they can craft and send a malicious ViewState that the server deserializes, potentially resulting in remote code execution. The risk stems from platform-level ASP.NET behavior rather than a defect introduced by ScreenConnect, and the ScreenConnect Client is not directly impacted, though the CVSS vector (PR:H) confirms exploitation requires already having high privileges on the host. An attacker who achieves this gains code execution on the server with the confidentiality, integrity, and availability impact reflected in the 7.2 High score. ScreenConnect 2025.4 mitigates the issue by disabling ViewState entirely and removing any dependency on it. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-06-02, indicating confirmed exploitation in the wild, with EPSS estimating a 3.4% chance of exploitation in the next 30 days (88th percentile).
    · ConnectWise ScreenConnect 25.2.3 and earlier; mitigated in 2025.4 (ViewState disabled) KEVlarge
  • A condition in the ScreenConnect server component may allow an actor with access to server-level cryptographic material used for authentication to obtain unauth
    A condition in the ScreenConnect server component may allow an actor with access to server-level cryptographic material used for authentication to obtain unauthorized access, including elevated privileges, in certain scenarios. ScreenConnect host and guest client agents are not independently affected by this CVE.

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