Host Header Injection (HHI) in the Hotspot Shield VPN client
Hotspot Shield VPN client, version 12.9.2.
INCIBE has coordinated the publication of a low severity vulnerability affecting the VPN client Hotspot Shield. The vulnerability has been discovered by Julen Garrido Estevez.
This vulnerability has been assigned the following code, CVSS v4.0 base score, CVSS vector and vulnerability type CWE:
- CVE-2025-40710: CVSS v4.0: 2.3 | CVSS AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N | CWE-74
There is no reported solution at this time.
CVE-2025-40710: Host Header Injection (HHI) vulnerability in the Hotspot Shield VPN client, which can induce unexpected behaviour when accessing third-party web applications through the VPN tunnel.
Although such applications do not present this vulnerability per se, the use of the tunnel, together with a forged Host header, can cause the VPN client to redirect or forward HTTP requests to servers other than those originally intended, leading to consequences such as open redirects or delivery of traffic to infrastructure controlled by an attacker. This does not imply a flaw in the target applications, but in how the VPN client internally handles outgoing headers and requests.
