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The vulnerability resides in the way nebula-mesh handles operator session tokens. When an operator authenticates, the system generates a 32-byte random hex value that serves as the session token. This token is sent directly in a cookie and is valid for 24 hours. The token is stored in the `operator_sessions` table, where the `token` column is defined as the PRIMARY KEY. The codebase reveals that `internal/models/operator.go:61` defines `OperatorSession.Token` to hold this plaintext token. When a session is created, `internal/store/sqlite_operators.go:590` executes an `INSERT` operation that writes the token verbatim into the database. Subsequent lookups, updates, and deletions of sessions—implemented at lines 603, 642, 681, and 698 in the same file—all use `WHERE token = ?` queries that compare against the plaintext value. This design means that any actor who gains read access to the database—whether through a backup, a filesystem snapshot, a direct file copy, or a SQL injection vulnerability—can retrieve every active session token. With these tokens, an attacker can impersonate any operator without needing credentials or further authentication. The issue mirrors a previously fixed enrollment-token flaw (GHSA-ghmh-jhmj-wcmf) and is particularly concerning because API keys and enrollment tokens are already stored as SHA256 hashes, yet session tokens were overlooked. The session tokens are ephemeral with a 24-hour TTL, so all active sessions can be invalidated upon deployment, but the underlying storage mechanism remains insecure until patched.
DailyCVE Form:
Platform: nebula-mesh
Version: All pre-patch
Vulnerability: Plaintext token storage
Severity: Critical
date: 2026-07-14
Prediction: 2026-07-21
What Undercode Say:
Check for plaintext tokens in the database
sqlite3 nebula-mgmt.db "SELECT token FROM operator_sessions;"
Dump all active session tokens
sqlite3 nebula-mgmt.db "SELECT token, expires_at FROM operator_sessions WHERE expires_at > datetime('now');"
Simulate token extraction from a backup
cat backup.sql | grep -E "INSERT INTO operator_sessions.VALUES"
Code snippet showing the insecure storage pattern (internal/store/sqlite_operators.go:590)
CreateOperatorSession inserts sess.Token verbatim
_, err := s.db.Exec(<code>INSERT INTO operator_sessions (token, operator_id, expires_at) VALUES (?, ?, ?)</code>, sess.Token, sess.OperatorID, sess.ExpiresAt)
Exploit:
An attacker with read access to the SQLite database (e.g., via an exposed backup, a misconfigured storage bucket, or a SQL injection flaw) can directly query the `operator_sessions` table. The `token` column contains the raw 32-byte hex values used for session cookies. The attacker copies any valid token (where `expires_at` is in the future) and injects it into their browser as the session cookie. The application will accept this token without any additional checks, granting the attacker full operator privileges, including the ability to manage nodes, modify configurations, and view sensitive network data.
Protection:
- Apply the official patch that migrates to storing SHA256 hashes of session tokens instead of plaintext values.
- As a workaround, restrict and encrypt all database backups, and ensure strict filesystem permissions on the database file.
- Rotate the operator database to invalidate all existing sessions immediately upon deployment of the fix.
- Consider using a dedicated secrets management solution or hardware security module (HSM) for token storage in high-security environments.
Impact:
Successful exploitation allows an attacker to completely compromise the operator account, leading to unauthorized control over the entire Nebula mesh network. This includes the ability to add or remove nodes, change VPN routing policies, and exfiltrate sensitive network topology information. Since session tokens are valid for 24 hours, the attacker has a significant window of opportunity. The vulnerability is particularly dangerous in shared or multi-tenant environments where database read access might be more easily obtained. The flaw undermines the security of the entire control plane and can lead to a full takeover of the VPN infrastructure.
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Sources:
Reported By: github.com
Extra Source Hub:
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