CVE-2025-27093 is an improper access control vulnerability (CWE-284) found in BishopFox's Sliver command and control (C2) framework, specifically in versions 1.5.43 and earlier, including the development version 1.6.0-dev. Sliver uses a custom Wireguard netstack to manage encrypted communications between implants and operators. The vulnerability stems from the netstack's failure to restrict traffic between Wireguard clients, allowing unrestricted peer-to-peer communication. This design flaw means that any compromised implant or client with access to the Wireguard network can communicate directly with other implants or operator nodes without proper access controls. Consequently, if an attacker manages to leak or recover Wireguard keypairs, they could leverage this unrestricted communication channel to attack the C2 operators themselves or access port forwardings that were intended to be isolated. The vulnerability is remotely exploitable over the network without requiring privileges but does require user interaction, such as implant deployment. The CVSS v3.1 score is 6.3 (medium), reflecting the moderate impact on confidentiality, integrity, and availability. Although no public exploits are known, the vulnerability poses a significant risk to the security posture of organizations relying on Sliver for offensive security operations, as it could facilitate lateral movement, data leakage, or unauthorized access within the C2 infrastructure.

For European organizations, especially those involved in offensive security, red teaming, or penetration testing using Sliver, this vulnerability could lead to unauthorized lateral movement within their C2 infrastructure. Attackers exploiting this flaw could compromise operator machines, intercept or manipulate command and control traffic, and gain access to sensitive operational data. This could undermine the confidentiality and integrity of red team operations and potentially expose sensitive internal security assessments. Additionally, the availability of the C2 infrastructure could be impacted if attackers disrupt communications or hijack port forwardings. Given the increasing reliance on such frameworks for security testing, exploitation could also damage organizational reputation and trust. The impact is particularly critical for organizations handling sensitive or classified information, such as government agencies, defense contractors, and critical infrastructure operators in Europe.

Organizations should upgrade Sliver to versions later than 1.5.43 or the stable release beyond 1.6.0-dev where this vulnerability is addressed. In the absence of an official patch, administrators should implement network segmentation and strict firewall rules to isolate Wireguard clients and prevent unauthorized inter-client communication. Employing strict key management practices to prevent key leakage is essential. Monitoring network traffic within the Wireguard interface for anomalous peer-to-peer connections can help detect exploitation attempts. Additionally, limiting implant deployment to trusted environments and enforcing multi-factor authentication for operator access can reduce risk. Regular audits of port forwarding configurations and restricting their exposure to only necessary implants will further mitigate potential abuse. Finally, organizations should maintain up-to-date incident response plans tailored to C2 infrastructure compromise scenarios.