CVE-2026-67357: ArcadeDB Information Disclosure Flaw

CVE-2026-67357 Overview

CVE-2026-67357 is an information disclosure vulnerability in ArcadeDB versions before 26.7.3. The flaw resides in the Model Context Protocol (MCP) get_server_settings tool, which returns the arcadedb.ha.clusterToken value in cleartext. Attackers with MCP access can retrieve the cluster token and reuse it in X-ArcadeDB-Cluster-Token and X-ArcadeDB-Forwarded-User headers to impersonate the root account. Successful exploitation results in full server compromise, including administrative control over databases and stored data. The issue is tracked under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor).

Critical Impact
Attackers with low-privilege MCP access can retrieve the cluster token, impersonate root via forwarded-user headers, and take full control of the ArcadeDB server.

Affected Products

ArcadeDB versions prior to 26.7.3
Deployments exposing the MCP get_server_settings tool
ArcadeDB clusters using arcadedb.ha.clusterToken for node authentication

Discovery Timeline

2026-08-02 - CVE-2026-67357 published to NVD
2026-08-03 - Last updated in NVD database

Technical Details for CVE-2026-67357

Vulnerability Analysis

ArcadeDB integrates with the Model Context Protocol (MCP) to expose administrative and introspection tools. The get_server_settings tool returns the server configuration, but does not redact sensitive keys. The arcadedb.ha.clusterToken setting is included in the response as cleartext.

The cluster token authenticates internal cluster traffic. ArcadeDB trusts requests that carry this token via the X-ArcadeDB-Cluster-Token header. When combined with the X-ArcadeDB-Forwarded-User header, the server accepts the specified identity without additional verification. An attacker supplies root as the forwarded user and bypasses standard authentication.

The attack requires MCP access at low privilege but no user interaction. Exploitation impacts confidentiality, integrity, and availability of the ArcadeDB deployment.

Root Cause

The root cause is improper output filtering in the MCP get_server_settings implementation. Configuration values containing secrets are serialized alongside benign settings without a deny-list or classification. The cluster token, which functions as a shared authentication secret, is treated as an ordinary configuration string.

Attack Vector

An attacker with MCP access invokes get_server_settings and extracts arcadedb.ha.clusterToken. The attacker then sends HTTP requests directly to the ArcadeDB server with two headers set: X-ArcadeDB-Cluster-Token containing the stolen token, and X-ArcadeDB-Forwarded-User set to root. The server processes these requests under root privileges, granting the attacker administrative control.

No verified public exploit code is available. See the GitHub Security Advisory and the VulnCheck Advisory for vendor-verified technical details.

Detection Methods for CVE-2026-67357

Indicators of Compromise

HTTP requests to ArcadeDB endpoints containing the X-ArcadeDB-Cluster-Token header from non-cluster peer IP addresses.
Requests carrying X-ArcadeDB-Forwarded-User: root originating from clients that are not authorized proxies.
MCP tool invocations of get_server_settings from user contexts that do not require configuration access.
Administrative operations on databases performed shortly after get_server_settings calls from the same session.

Detection Strategies

Inspect ArcadeDB access logs for the co-occurrence of X-ArcadeDB-Cluster-Token and X-ArcadeDB-Forwarded-User headers on requests reaching the HTTP API.
Correlate MCP audit logs of get_server_settings calls with subsequent authenticated activity as root.
Alert on any external source address presenting cluster-authentication headers, since these should be limited to intra-cluster traffic.

Monitoring Recommendations

Forward ArcadeDB HTTP and MCP logs to a centralized logging platform and retain them for retrospective analysis.
Baseline normal MCP tool usage per user and flag anomalous invocation of configuration-reading tools.
Monitor for creation of new administrative users or unexpected schema changes following MCP configuration queries.

How to Mitigate CVE-2026-67357

Immediate Actions Required

Upgrade ArcadeDB to version 26.7.3 or later on all server and cluster nodes.
Rotate the arcadedb.ha.clusterToken value on every node after upgrading, since prior tokens may be compromised.
Restrict MCP access to trusted administrative identities and remove access for accounts that do not require configuration inspection.
Review access logs for prior use of X-ArcadeDB-Cluster-Token and X-ArcadeDB-Forwarded-User headers from unexpected sources.

Patch Information

The vulnerability is fixed in ArcadeDB 26.7.3. The patch removes sensitive keys, including arcadedb.ha.clusterToken, from the response of the MCP get_server_settings tool. Refer to the GitHub Security Advisory GHSA-p9wc-4fhr-78wm for the official fix details.

Workarounds

Disable the MCP get_server_settings tool if it is not required for operations.
Place ArcadeDB HTTP endpoints behind a reverse proxy that strips X-ArcadeDB-Cluster-Token and X-ArcadeDB-Forwarded-User headers from untrusted sources.
Restrict cluster communication to a private network segment inaccessible to application clients and MCP consumers.
Rotate the cluster token on a regular schedule until the upgrade is applied.

bash

# Example reverse-proxy header stripping (nginx)
proxy_set_header X-ArcadeDB-Cluster-Token "";
proxy_set_header X-ArcadeDB-Forwarded-User "";