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CVE-2025-3935 is a ViewState code-injection and deserialization vulnerability affecting ConnectWise ScreenConnect 25.2.3 and earlier. ASP.NET Web Forms ViewState data is Base64-encoded and protected by ASP.NET machine keys. An attacker who obtains the affected server's machine keys can forge a malicious ViewState payload that the ScreenConnect website accepts, potentially causing remote code execution on the underlying server. The issue arises from ASP.NET platform-level ViewState behavior rather than a ScreenConnect-specific implementation change, and it does not directly affect the ScreenConnect Client.
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What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
33 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A previously exploited ScreenConnect vulnerability that was used to steal secret machine keys from a ScreenConnect server.
An improper authentication vulnerability in ScreenConnect (CVE-2025-3935) that enables ViewState code injection attacks, exploited in a breach attributed to a suspected nation-state actor.
A deserialization vulnerability in ASP.NET ViewState within ConnectWise ScreenConnect that can be exploited to compromise affected environments; it was added to CISA’s KEV, indicating real-world exploitation.
An authentication bypass vulnerability in ConnectWise ScreenConnect that can enable unauthorized remote access to management consoles.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.