CVE-2026-10054

In affected versions of Eclipse Theia (1.8.1 and later), the browser backend exposes privileged terminal RPC over WebSocket (/services/shell-terminal, /services/terminals/:id) without service-level authentication. WebSocket origin validation in @theia/core is fail-open: connections are accepted when the Origin header is missing or when no THEIA_HOSTS allowlist is configured (the default). The Socket.IO integration additionally replaces the real Origin header with a client-supplied fix-origin header that an attacker can control or omit. As a result, a foreign-origin web page visited by a user with a running Theia instance can open the /services WebSocket namespace, invoke terminal creation, attach to the resulting terminal data channel, execute arbitrary OS commands, and read their output. This affects both local developer setups (drive-by attack) and hosted or tunneled deployments without strong external authentication. A fix is in development that enforces same-origin validation by default, removes trust in the fix-origin header, gates HTTP and WebSocket access on a SameSite=Strict; HttpOnly connection-token cookie, and sanitizes shell terminal creation options.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/eclipse-theia/theia/security/advisories/GHSA-78g8-vm3p-97c6
https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/376

Configurations

No configuration.

History

03 Jul 2026, 11:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-03 11:16

Updated : 2026-07-07 05:16

NVD link : CVE-2026-10054

Mitre link : CVE-2026-10054

CVE.ORG link : CVE-2026-10054

JSON object : View

Products Affected

No product.

CWE

CWE-306

Missing Authentication for Critical Function

CWE-1385

Missing Origin Validation in WebSockets

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