CVE-2025-3935 ConnectWise ScreenConnect: login or permission bypass
In plain words: A door that should be locked is not: part of the system can be reached without a valid login or permission. The attacker gets in as a user or administrator without knowing a password.
Confirmed exploited by CISA on · US federal patch deadline Jun 23, 2025
What to do
- Install ConnectWise's security update for ScreenConnect. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Keep a list of every internet-facing server you run so nothing is forgotten.
- Patch anything in this catalog first, ahead of normal patch cycles.
- Put admin and file-transfer apps behind a VPN or single sign-on instead of the open internet.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: Mass data theft and ransomware: a single flaw in a file-transfer or email server has exposed thousands of organisations at once.
The details
- Official name
- ConnectWise ScreenConnect Improper Authentication Vulnerability
- Product
- ConnectWise ScreenConnect
- CISA description
- ConnectWise ScreenConnect contains an improper authentication vulnerability. This vulnerability could allow a ViewState code injection attack, which could allow remote code execution if machine keys are compromised.
- Type of flaw
- Login or permission bypass (CWE-287)
- Confirmed exploited
- Jun 2, 2025
- US federal patch deadline
- Jun 23, 2025
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Answering about CVE-2025-3935 ·
Questions about CVE-2025-3935
Is CVE-2025-3935 being exploited?
Yes. CISA added CVE-2025-3935 to its Known Exploited Vulnerabilities catalog on Jun 2, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2025-3935?
Install ConnectWise's security update for ScreenConnect. If no update exists, follow the vendor's workaround or stop using the product until one ships. Keep a list of every internet-facing server you run so nothing is forgotten.
Am I affected by CVE-2025-3935?
Only if you use ConnectWise ScreenConnect. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.