CVE-2026-34227
HIGHSliver One-Click Remote Access: Insecure CORS & Unauthenticated MCP Interface
Title source: cnaExploitation Summary
EIP tracks 1 public exploit for CVE-2026-34227. PoCs published by skoveit.
AI-analyzed exploit summary This repository contains a functional proof-of-concept exploit for CVE-2026-34227, demonstrating an unauthenticated CORS bypass in Sliver's MCP server via Server-Sent Events (SSE). The PoC leverages the lack of Content-Type validation to bypass browser preflight checks and exfiltrate data cross-origin.
Description
Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to version 1.7.4, a single click on a malicious link gives an unauthenticated attacker immediate, silent control over every active C2 session or beacon, capable of exfiltrating all collected target data (e.g. SSH keys, ntds.dit) or destroying the entire compromised infrastructure, entirely through the operator's own browser. This issue has been patched in version 1.7.4.
Exploits (1)
This repository contains a functional proof-of-concept exploit for CVE-2026-34227, demonstrating an unauthenticated CORS bypass in Sliver's MCP server via Server-Sent Events (SSE). The PoC leverages the lack of Content-Type validation to bypass browser preflight checks and exfiltrate data cross-origin.
References (1)
Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H