PureVPN Linux apps found to leak IPv6 traffic and mess with your firewall – here’s how to secure your data

• A security researcher has found flaws with two of PureVPN's Linux clients
• The impacted apps may leak IPv6 traffic under certain circumstances and interfere with local firewall settings
• PureVPN has confirmed the team is working to patch these flaws by mid-October

A security researcher has found two issues with Pure VPN's Linux applications – one affecting IPv6 traffic and the other the system firewall.

Andreas, a Greek Linux expert who operates under the name of Anagogistis, discovered that both the GUI v2.10.0 and CLI v2.0.1 versions of PureVPN's Linux clients can leak IPv6 traffic outside the encrypted tunnel.

When connecting with both these Linux VPN apps, PureVPN also interferes with the local firewall settings, which "may affect users relying on persistent firewall rules for local security," Anagogistis notes in his report.

After the reported findings allegedly went unanswered for over three weeks, on Friday (September 19, 2025), PureVPN confirmed the team is working to patch these flaws by mid-October. The provider also ensures that no other platforms (Windows, macOS, Android, iOS) are affected.

Both the security expert and the provider are suggesting some workarounds to all PureVPN's Linux users until the fix is released.

IPv6 leak and firewall misconfigurations – what's at stake for PureVPN users

As per Anagogistis' report published on Wednesday, September 17, both PureVPN's Linux clients (GUI v2.10.0 and CLI v2.0.1) may leak IPv6 under some specific conditions.

For example, during the test, leaks occur after a network transition, such as suspending or resuming an Ethernet connection or toggling Wi-Fi.

"As far as I can tell, there is no leak during normal sessions without network disruption," writes Anagogistis.

When an IPv6 leak occurs, websites or email services could have access to users' real locations and track their activities – exactly what you are trying to prevent by using the best VPN services.

Both these Linux clients also show signs of firewall misconfigurations.

Specifically, after the app connects, it replaces existing iptables rules (meaning the command lines that define how the Linux kernel handles the data packets). When the user disconnects the virtual private network (VPN) software, however, the original device's settings fail to be restored.

This leaves the system in a different firewall state compared to its initial configuration. Something that, as PureVPN explains, "may leave the device with fewer protections than the user had in place before connecting to the VPN."

PureVPN's Linux apps were both tested and reproduced on Ubuntu 24.04.3 LTS with kernel 6.8 and iptables-nft backend.

We contacted PureVPN to know more about the risk for users and what's behind these flaws, but we are still waiting for a reply at the time of writing.

How to stay safe

While the team at PureVPN work on releasing a technical fix to these vulnerabilities, you should seriously consider to take some active steps to protect your data.

PureVPN suggests users should:

• Disable IPv6 manually at the system level.
• Reapply firewall rules after disconnecting from PureVPN.
• Use IPv4-only connections where possible until the patched client is released.

All in all, PureVPN said: "While this issue is limited to Linux clients, we recognize the seriousness of IPv6 leaks and firewall handling. We are moving quickly to release a fix and reinforcing our internal processes to ensure faster acknowledgments and fixes in the future."

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