CVE-2026-53603 nebula-mesh: Operator session tokens stored in plaintext in the database
Attackers with database access can steal plaintext operator session tokens to hijack admin sessions in nebula-mesh.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53603?
CVE-2026-53603 is a high-severity vulnerability in forgekeep nebula-mesh, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
nebula-mesh is a self-hosted control plane for Slack Nebula mesh VPN. Prior to version 0.3.8, Operator session tokens are stored in plaintext in the operator_sessions table (the token column is the PRIMARY KEY). The session token is a 32-byte random hex value sent directly in a cookie and valid for 24 hours. Anyone who can read the database (backup, snapshot, file copy, or SQL-level disclosure) obtains every active session token and can hijack operator sessions directly, with no further authentication. This issue has been patched in version 0.3.8.
Which versions are affected by CVE-2026-53603?
3 open source packages ship an affected version, including github.com/forgekeep/nebula-mesh.
| Package | Affected | Fixed in |
|---|---|---|
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.8 |
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.8 |
github.com/forgekeep/nebula-mesh Go | All versions | 0.3.8 |
How do I fix CVE-2026-53603?
Upgrade github.com/forgekeep/nebula-mesh to 0.3.8 or later.
Is CVE-2026-53603 being exploited?
There is no known exploitation of CVE-2026-53603 in the wild and no public exploit code.
Sources
Also known as GHSA-q4vm-pq3q-8wgq, GO-2026-5991.