Viscosity 1.13 is now available for both macOS and Windows! This is one of our biggest updates yet, especially for Windows, with a huge number of improvements, new features, performance optimisations, security improvements, and bug fixes.

The most obvious change is the refreshed design on Windows, giving both the Settings window and main menu a more modern look. We've also added some quality-of-life improvements to navigating the main menu when working with a large number of connections, including better mouse navigation and scrolling support.

We've also significantly overhauled Viscosity's VPN network adapter driver, offering substantial performance improvements on Windows. If your VPN connection's speed was previously limited by client-side performance, you should notice a meaningful throughput increase.

Continuing our focus on performance, the macOS version also includes optimisations to both its TAP and obfuscation engines. Users should see a bump in the maximum performance possible when using a TAP connection. Obfuscation has been optimised to significantly cut down connection time, with near-instant connections to the obfuscation server now possible, while also improving both latency and throughput.

Viscosity's PKCS#11 support (used by tokens and smartcards) has also been reworked on both macOS and Windows, making it more powerful while also offering a much more intuitive selection interface. Viscosity will now display an easy-to-use certificate selection menu with a user-friendly display of both certificate and token information. And for system administrators, Viscosity now supports the PKCS#11 URI scheme, including additional matching fields, making more precise automatic selection possible.

On Windows, we've also rewritten parts of Viscosity's interface to improve performance when there is no graphics acceleration available on the local machine (such as in a virtual machine with limited graphics support). Elements like the Settings window should feel much more responsive when running in such environments.

This version also transitions from OpenSSL version 3.0 to version 3.5. As well as bringing important security updates, OpenSSL 3.5 also brings post-quantum cryptography (PQC) support. Post-quantum key exchange mechanisms, such as X25519MLKEM768, can now be used for OpenVPN connections (assuming the OpenVPN server is suitably updated), helping protect against "harvest now, decrypt later" attacks where an attacker records encrypted VPN traffic today and attempts to decrypt it in the future using a quantum computer.

OpenVPN itself has also been updated to version 2.6.21. This update addresses a number of security issues which affect OpenVPN clients, so we recommend updating to Viscosity version 1.13 as soon as possible.

Finally, this update drops support for macOS 13 (macOS 14 or later is now required), and for Windows 10 21H1 and older (Windows 10 21H2 or later is now required). Older Viscosity releases can still be found at the Legacy Downloads page if required.

Version 1.13 Mac Release Notes:

The 1.13 update can be automatically installed from inside Viscosity, or downloaded and manually installed. For support with this version please visit our support section.