CVE-2024-3661

Published: May 9, 2024Last modified: June 18, 2025

Description

DHCP can add routes to a client’s routing table via the classless static route option (121). VPN-based security solutions that rely on routes to redirect traffic can be forced to leak traffic over the physical interface. An attacker on the same local network can read, disrupt, or possibly modify network traffic that was expected to be protected by the VPN.

Severity score breakdown

Notes

other VPN-providing packages may be affected

Status

References

• https://arstechnica.com/security/2024/05/novel-attack-against-virtually-all-vpn-apps-neuters-their-entire-purpose/
• https://bst.cisco.com/quickview/bug/CSCwk05814
• https://datatracker.ietf.org/doc/html/rfc2131#section-7
• https://datatracker.ietf.org/doc/html/rfc3442#section-7
• https://fortiguard.fortinet.com/psirt/FG-IR-24-170
• https://issuetracker.google.com/issues/263721377
• https://krebsonsecurity.com/2024/05/why-your-vpn-may-not-be-as-secure-as-it-claims/
• https://lowendtalk.com/discussion/188857/a-rogue-dhcp-server-within-your-network-can-and-will-hijack-your-vpn-traffic
• https://mullvad.net/en/blog/evaluating-the-impact-of-tunnelvision
• https://my.f5.com/manage/s/article/K000139553
• https://news.ycombinator.com/item?id=40279632
• https://news.ycombinator.com/item?id=40284111
• https://security.paloaltonetworks.com/CVE-2024-3661
• https://support.citrix.com/article/CTX677069/cloud-software-group-security-advisory-for-cve20243661
• https://tunnelvisionbug.com/
• https://www.agwa.name/blog/post/hardening_openvpn_for_def_con
• https://www.leviathansecurity.com/research/tunnelvision
• https://www.theregister.com/2024/05/07/vpn_tunnelvision_dhcp/
• https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2024-00009
• https://www.zscaler.com/blogs/security-research/cve-2024-3661-k-tunnelvision-exposes-vpn-bypass-vulnerability