# CVE-2025-3935: ConnectWise ScreenConnect Improper Authentication

> Attackers with privileged access to machine keys can inject malicious ViewState data to achieve remote code execution on the server.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 2 Jun 2025 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Apr 2025
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-qjrp-xr9r-wmrg

## What is CVE-2025-3935?

CVE-2025-3935 is a high-severity unsafe deserialization vulnerability in ConnectWise ScreenConnect, published on 25 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ScreenConnect versions 25.2.3 and earlier versions may be susceptible to a ViewState code injection attack. ASP.NET Web Forms use ViewState to preserve page and control state, with data encoded using Base64 protected by machine keys. 
It is important to note that to obtain these machine keys, privileged system level access must be obtained. 

If these machine keys are compromised, attackers could create and send a malicious ViewState to the website, potentially leading to remote code execution on the server. 

The risk does not originate from a vulnerability introduced by ScreenConnect, but from platform level behavior.  This had no direct impact to ScreenConnect Client. ScreenConnect 2025.4 patch disables ViewState and removes any dependency on it.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2025-3935?

It affects 1 product.


Products: Connectwise Screenconnect.

## How do I fix CVE-2025-3935?

No fix has been published for CVE-2025-3935 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 23 Jun 2025.

## Is CVE-2025-3935 being exploited?

Yes. Attackers have exploited CVE-2025-3935 in the wild since at least 2 Jun 2025.

## Other vulnerabilities in ConnectWise ScreenConnect

- [CVE-2024-1709](https://insights.sbomify.com/CVE-2024-1709/): ConnectWise ScreenConnect Authentication Bypass (critical 10.0, exploited in the wild)
- [CVE-2026-84869](https://insights.sbomify.com/CVE-2026-84869/): ConnectWise ScreenConnect Improper Privilege Management and Missing Authorization (critical 9.9, exploited in the wild)
- [CVE-2024-1708](https://insights.sbomify.com/CVE-2024-1708/): ConnectWise ScreenConnect Path Traversal (high 8.4, exploited in the wild)
- [CVE-2025-14265](https://insights.sbomify.com/CVE-2025-14265/): Improper server-side validation in ScreenConnect extension framework (critical 9.1)
- [CVE-2025-14823](https://insights.sbomify.com/CVE-2025-14823/): Certificate Signing Extension Returns Encrypted Values (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-3935 and fix it if it is affected.

What it is: CVE-2025-3935 is a high-severity unsafe deserialization vulnerability in ConnectWise ScreenConnect, published on 25 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2025-3935 in the wild since at least 2 Jun 2025.

Affected product: ConnectWise ScreenConnect. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-3935/ (Markdown: https://insights.sbomify.com/CVE-2025-3935/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-3935
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-3935
- OSV: https://osv.dev/vulnerability/CVE-2025-3935

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-3935/
Summaries are generated and may contain mistakes; the official description above is the record.