# CVE-2026-10054

## Summary

- **CVE ID:** CVE-2026-10054
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
- **CWE:** CWE-1385, CWE-306
- **Published:** Jul 3, 2026
- **Last Modified:** Jul 8, 2026

## Description

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.

## Affected Products

- Eclipse Foundation — Eclipse Theia (1.8.1)

## References

- [CNA](https://github.com/eclipse-theia/theia/security/advisories/GHSA-78g8-vm3p-97c6)
- [CNA](https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/376)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.22%
- **EPSS Percentile:** 12.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._