CVE intelligence and bounded remediation

CVE-2024-3661 — DHCP can add routes to a client’s routing table via the classless static route option (121)

High CVSS 7.6

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
High
CVSS
7.6 (3.1)
Published
2024-05-06
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-306, CWE-501

Affected products

  • fortinet / forticlient
  • fortinet / forticlient / 7.4.0
  • cisco / anyconnect_vpn_client
  • cisco / secure_client
  • paloaltonetworks / globalprotect

Showing 5 representative product identities from 26 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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