# CVE-2026-10054: Eclipse Theia remote command execution via cross-origin WebSocket access

Source: https://junglewise.ai/threats/cve-2026-10054-eclipse-theia-remote-command-execution-via-cross-origin-websocket  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-03. Updated: 2026-07-03  
License: CC BY 4.0 with a link back

CVE-2026-10054 · Severity: high · CVSS 8.8 · Published 2026-07-03

Eclipse Theia, an extensible platform for building IDE-like applications, contains a vulnerability that allows malicious websites to execute commands on a developer's machine. If a user visits a compromised or malicious webpage while running a Theia-based application, the webpage can secretly connect to the application's terminal service. This allows an attacker to run arbitrary code, access private files, and steal sensitive data from the development environment.

Technologies: [Eclipse Foundation Theia](https://junglewise.ai/threats/technologies/theia). Vendors: [Eclipse Foundation](https://junglewise.ai/threats/vendors/eclipse-foundation).

## Quick answers

**Is CVE-2026-10054 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10054 being exploited in the wild.

**How severe is CVE-2026-10054?** High severity, with a CVSS score of 8.8, published 3 July 2026.

**Which products and versions are affected?** Eclipse Foundation Theia >= 1.8.1, < 1.73.0.

**Is there a fix for CVE-2026-10054?** A patch was published on 2026-07-03: Fix released in version 1.73.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-10054 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-10054?** Check whether you run Eclipse Foundation Theia at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

Eclipse Theia (versions 1.8.1 to 1.72.x) exposes terminal RPC services (/services/shell-terminal) over WebSockets without service-level authentication. The vulnerability stems from a fail-open WebSocket origin validation in @theia/core that accepts connections when the Origin header is missing or when THEIA_HOSTS is unconfigured. Furthermore, the Socket.IO integration allows a client-supplied 'fix-origin' header to override the actual Origin header. An attacker can exploit this via a drive-by attack where a victim visits a malicious site; the site then connects to the local or hosted Theia backend, creates a terminal, and executes arbitrary OS commands via the PTY spawn path. A fix in version 1.73.0 enforces same-origin validation and introduces a connection-token cookie.

## Affected products

- Eclipse Foundation Theia >= 1.8.1, < 1.73.0

## Timeline

- 2026-03-11: other: Vulnerability reproduction and verification by researcher.
- 2026-07-03: advisory: Public disclosure of GHSA-78g8-vm3p-97c6 and CVE-2026-10054.
- 2026-07-03: patched: Fix released in version 1.73.0.

## References

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

## Related threats

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