Mullvad VPN fingerprinting flaw can allow websites and services to link your activity across different VPN servers, even though it does not reveal your actual identity. Mullvad, the privacy-focused VPN provider, disclosed the issue on May 15, 2026, after discovering that its method for assigning exit IP addresses could expose enough information for fingerprinting between servers. The vulnerability affects users who switch between VPN servers, potentially allowing someone to determine that the same person who connected from one Mullvad server later connected from another.
Key Takeaways
- Mullvad VPN fingerprinting flaw allows cross-server activity linking without revealing user identity
- The issue stems from the relationship between WireGuard keys and exit IP address assignments
- Temporary fix: log out and back into the app when switching servers to regenerate your WireGuard key
- Permanent solution is in testing and will roll out to servers in coming weeks
- The flaw does not compromise all VPN users equally—it primarily affects those with threat models that include cross-server tracking
What Mullvad VPN Fingerprinting Flaw Actually Does
The Mullvad VPN fingerprinting flaw is not a complete privacy collapse. It does not reveal who you are in the real world, nor does it expose your browsing traffic or passwords. Instead, it creates a linkable pattern: if you connect to a Mullvad server, then switch to a different Mullvad server, a website or service could theoretically determine that the same user made both connections. This happens because the current exit IP assignment method reveals enough information to correlate your sessions across servers. The flaw is specific to switching between Mullvad’s own VPN servers, not a general weakness in how VPNs work.
Think of it this way: a VPN is supposed to mask your identity and location by routing your traffic through an encrypted tunnel. The Mullvad VPN fingerprinting flaw pokes a small hole in that tunnel—not large enough to see who you are, but large enough for someone to notice you passed through twice. For users whose only concern is hiding their IP address from websites, this flaw may not matter. For users worried about being tracked across sessions or correlated over time, it is a meaningful privacy leak.
Mullvad VPN Fingerprinting Flaw: Temporary Workaround
Mullvad has recommended a simple but manual workaround while the permanent fix is being tested and prepared for rollout. If you need to switch VPN servers, follow these steps to prevent fingerprinting across your sessions. First, open the Mullvad app and log out completely. Next, log back in immediately. This action regenerates your WireGuard key—the cryptographic identifier that ties your connection to a specific exit IP address—and assigns you a new internal IP address on the Mullvad network. By doing this every time you switch servers, you break the linkage that would otherwise allow fingerprinting. The process takes less than a minute and requires no technical knowledge.
This workaround is not a perfect solution. It is manual, which means users must remember to do it every time they switch servers. It also creates a brief moment when your connection is interrupted, during which your traffic is not protected by the VPN. For most users, this window is negligible, but it is worth knowing. Mullvad’s recommendation is to switch servers only when necessary, then apply the logout-and-login fix immediately afterward.
When the Permanent Fix Arrives
Mullvad is developing a new method for assigning exit IP addresses that will not reveal which exit address is used on another VPN server or by another user on the same server. This architectural change addresses the root cause of the Mullvad VPN fingerprinting flaw rather than asking users to work around it manually. The company says the fix is currently being tested and is planned to start rolling out to its VPN servers in the coming weeks. No exact rollout date has been announced, so users should not expect the fix to be live immediately.
Once the permanent fix is deployed, the temporary workaround will no longer be necessary. Mullvad users will be able to switch servers freely without the risk of cross-server fingerprinting. The rollout will likely be gradual across Mullvad’s server network, so some servers may receive the fix before others. Users should monitor Mullvad’s official blog or security advisories for updates on when the fix reaches their region or preferred servers.
How This Compares to Other Privacy Tools
Mullvad has built a reputation on privacy-first design, including tools like Mullvad Browser, which includes defenses against browser fingerprinting. The Mullvad VPN fingerprinting flaw reveals that even privacy-focused companies can overlook subtle linkage issues in their infrastructure. Tor Browser, by contrast, uses a different approach—rotating through a network of volunteer-run relays where users cannot easily choose which server to exit from, which reduces the opportunity for cross-server fingerprinting. However, Tor is significantly slower than VPN services like Mullvad because of its design trade-offs. Mullvad’s approach prioritizes speed and usability while still aiming for strong privacy, which is why the flaw matters: users chose Mullvad specifically because they trusted it to prevent this kind of tracking.
Should You Worry Right Now?
The answer depends on your threat model. If you are concerned about an adversary linking your activity across VPN servers—such as a website trying to correlate your behavior over time despite your VPN use—then yes, you should apply the temporary workaround when switching servers. If you are primarily using Mullvad to hide your IP address from websites or your internet service provider, the Mullvad VPN fingerprinting flaw is a lower-priority issue. The vulnerability does not expose your real identity, does not decrypt your traffic, and does not affect users who stay on a single server for extended periods.
Most casual VPN users will not notice the impact of this flaw in their daily lives. However, journalists, activists, or anyone with a sophisticated adversary should take the temporary workaround seriously until the permanent fix is deployed. The good news is that Mullvad disclosed the issue proactively and is working on a fix. The company did not hide the problem or minimize its severity, which is a sign of responsible security practices.
FAQ: Mullvad VPN Fingerprinting Flaw
Does the Mullvad VPN fingerprinting flaw reveal my real identity?
No. The flaw does not reveal your name, location, or any personally identifiable information. It only allows a website or service to determine that the same user connected from two different Mullvad servers at different times. Your actual identity remains hidden behind the VPN.
Do I need to switch servers frequently to be at risk?
Not necessarily. The risk depends on your threat model. If you switch servers once a week, the flaw could still create a linkable pattern. If you never switch servers, the flaw does not affect you. Apply the temporary workaround only when you actually need to change servers.
Will my data be stolen because of this flaw?
The Mullvad VPN fingerprinting flaw does not expose your data, passwords, or browsing history. It creates a tracking pattern that could be used to correlate your sessions across servers, but it does not compromise the encryption or security of your VPN connection itself.
The Mullvad VPN fingerprinting flaw is a reminder that even privacy-focused services are not immune to subtle architectural issues. The company’s quick disclosure and commitment to a permanent fix demonstrate responsible handling of the issue. For now, users who switch servers regularly should apply the temporary workaround—logout and login—to prevent cross-server fingerprinting. Once the fix rolls out in the coming weeks, this manual step will no longer be necessary, and Mullvad’s privacy protections will be more robust than before.
Edited by the All Things Geek team.
Source: Tom's Guide
