CVE-2024-3661

high-risk
Published 2024-05-06

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.

Do I need to act?

~
2.9% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.6/10 High
ADJACENT_NETWORK / LOW complexity

Affected Products (20)

Anyconnect Vpn Client
Secure Client
Secure Access Client
Ipsec Mobile Vpn Client
Ipsec Mobile Vpn Client
Mobile Vpn With Ssl
Mobile Vpn With Ssl

Affected Vendors

Cisco F5 Citrix Watchguard Fortinet Paloaltonetworks Zscaler

References (40)

Exploit https://arstechnica.com/security/2024/05/novel-attack-against-virtually-all-vpn-...
Third Party Advisory https://bst.cisco.com/quickview/bug/CSCwk05814
Related https://datatracker.ietf.org/doc/html/rfc2131#section-7
Related https://datatracker.ietf.org/doc/html/rfc3442#section-7
Vendor Advisory https://fortiguard.fortinet.com/psirt/FG-IR-24-170
Issue Tracking https://issuetracker.google.com/issues/263721377
Exploit https://krebsonsecurity.com/2024/05/why-your-vpn-may-not-be-as-secure-as-it-clai...
Issue Tracking https://lowendtalk.com/discussion/188857/a-rogue-dhcp-server-within-your-network...
Third Party Advisory https://mullvad.net/en/blog/evaluating-the-impact-of-tunnelvision
Vendor Advisory https://my.f5.com/manage/s/article/K000139553
Issue Tracking https://news.ycombinator.com/item?id=40279632
Issue Tracking https://news.ycombinator.com/item?id=40284111
Vendor Advisory https://security.paloaltonetworks.com/CVE-2024-3661
Vendor Advisory https://support.citrix.com/article/CTX677069/cloud-software-group-security-advis...
Exploit https://tunnelvisionbug.com/
Related https://www.agwa.name/blog/post/hardening_openvpn_for_def_con
Third Party Advisory https://www.leviathansecurity.com/research/tunnelvision
Exploit https://www.theregister.com/2024/05/07/vpn_tunnelvision_dhcp/
Mitigation https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2024-00009
Exploit https://www.zscaler.com/blogs/security-research/cve-2024-3661-k-tunnelvision-exp...
and 20 more references
50
/ 100
high-risk
Severity 24/34 · High
Exploitability 6/34 · Minimal
Exposure 20/34 · Moderate