vulnerability
Ubuntu: (CVE-2023-36671): openconnect vulnerability
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 6 | (AV:L/AC:H/Au:N/C:C/I:C/A:N) | Aug 9, 2023 | Jun 26, 2025 | Mar 27, 2026 |
Description
An issue was discovered in the Clario VPN client through 5.9.1.1662 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. This allows an adversary to trick the victim into sending plaintext traffic to the VPN server's IP address and thereby deanonymize the victim. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "ServerIP attack for only traffic to the real IP address of the VPN server" rather than to only Clario.
Solution
References
- CVE-2023-36671
- https://attackerkb.com/topics/CVE-2023-36671
- CWE-319
- EUVD-EUVD-2023-40614
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-40614
- https://openvpn.net/security-advisory/statement-regarding-tunnelcrack-vulnerabilities/
- https://papers.mathyvanhoef.com/usenix2023-tunnelcrack.pdf
- https://tunnelcrack.mathyvanhoef.com/details.html
- https://www.cve.org/CVERecord?id=CVE-2023-36671
- https://www.softether.org/9-about/News/905-TunnelCrack
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