Vulnerability · Published Aug 9, 2023 · Assigned by mitre
CVE-2023-36673
High 7.3
In plain English
A high-severity security flaw in the openconnect package (Ubuntu). Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities).
Official description
An issue was discovered in Avira Phantom VPN through 2.23.1 for macOS. The VPN client insecurely configures the operating system such that all IP traffic to the VPN server's IP address is sent in plaintext outside the VPN tunnel, even if this traffic is not generated by the VPN client, while simultaneously using plaintext DNS to look up the VPN server's IP address. This allows an adversary to trick the victim into sending traffic to arbitrary IP addresses in plaintext outside the VPN tunnel. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "ServerIP attack, combined with DNS spoofing, that can leak traffic to an arbitrary IP address" rather than to only Avira Phantom VPN.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | openconnect | no fix listed | UBUNTU-CVE-2023-36673 |
| Ubuntu:24.04:LTS | openconnect | no fix listed | UBUNTU-CVE-2023-36673 |
| Ubuntu:22.04:LTS | softether-vpn | no fix listed | UBUNTU-CVE-2023-36673 |
| Ubuntu:24.04:LTS | softether-vpn | no fix listed | UBUNTU-CVE-2023-36673 |