The vulnerability arises from insecure CORS rules and an unauthenticated MCP interface in the Sliver C2 framework, allowing a single click on a malicious link to grant an attacker silent, privileged control of all active sessions. The attacker can then exfiltrate sensitive data such as SSH keys and Ntds.dit files or even destroy the entire compromised environment. This flaw is the result of an authentication bypass (CWE‑306) combined with unrestricted control over managed sessions (CWE‑942).

Sliver, a command and control platform developed by BishopFox, is impacted in all releases prior to 1.7.4. The custom Wireguard netstack and MCP interface in those versions allow unauthorized users to gain control of every beacon from a web browser. Version 1.7.4 contains the patch that removes the insecure CORS configuration and authenticates MCP access.

With a CVSS score of 5.9 the flaw carries medium severity, and its exploitability is not quantified by EPSS data. Because the attack can be performed by simply clicking a link in a browser, it is easy to replicate without prior knowledge or credentials. The vulnerability is not listed in the CISA KEV catalog, but the potential for widespread exposure to compromised sessions makes immediate remediation critical.