What is CVE-2025-3935?
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.
The record classifies CVE-2025-3935 under weakness class CWE-502. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 533 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 8.1 — HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS (FIRST)
- 3.5% probability of exploitation in the next 30 days, higher than 88.8% of all scored CVEs
- CISA KEV
- Listed since 2025-06-02, federal remediation deadline 2025-06-23
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2025-04-25, last modified 2026-02-26
Is CVE-2025-3935 being exploited?
CISA added CVE-2025-3935 to the Known Exploited Vulnerabilities catalog on 2025-06-02, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2025-06-23 under BOD 22-01. Weaponised exploit code for CVE-2025-3935 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 45 in the Threadlinqs vulnerability feed.
- trickest/cve (trickest)
Affected products and versions
- ConnectWise: ScreenConnect
How to fix CVE-2025-3935
Vendor advisory: https://www.connectwise.com/company/trust/advisories. Because CVE-2025-3935 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2025-06-23. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2025-3935
1 tracked threat in the Threadlinqs corpus references CVE-2025-3935, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, NVD, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.