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OpenClaw: MCP Streamable HTTP redirects could forward configured custom headers to another origin

High severity GitHub Reviewed Published May 28, 2026 in openclaw/openclaw • Updated Jun 17, 2026

Package

npm openclaw (npm)

Affected versions

< 2026.5.12

Patched versions

2026.5.12

Description

Summary

OpenClaw supports remote MCP Streamable HTTP servers with operator-configured custom headers. In affected releases, those headers could be forwarded when the MCP endpoint responded with a cross-origin redirect.

This issue is limited to configured MCP Streamable HTTP servers that use custom headers. It does not expose unrelated OpenClaw credentials.

Affected configurations

This affects deployments where an MCP server is configured with:

  • transportType: "streamable-http"
  • sensitive custom headers under mcp.servers.*.headers
  • an MCP endpoint that is malicious, compromised, or able to redirect to another origin

Impact

Custom MCP headers, such as API keys or tenant-routing headers, could be sent to the redirect target. The exposed credential scope depends on the header the operator configured for that MCP server.

Patched Versions

The first stable patched version is 2026.5.12.

Mitigations

Upgrade to openclaw@2026.5.8 or later. Before upgrading, avoid custom MCP headers with servers you do not fully trust, and rotate any MCP-specific credentials that may have been exposed by a redirecting endpoint.

References

@steipete steipete published to openclaw/openclaw May 28, 2026
Published to the GitHub Advisory Database Jun 17, 2026
Reviewed Jun 17, 2026
Last updated Jun 17, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

EPSS score

Weaknesses

Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Learn more on MITRE.

CVE ID

CVE-2026-53840

GHSA ID

GHSA-rjxq-qqhf-8hwh

Source code

Credits

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