# CVE-2026-10054: Missing authorization in Eclipse Theia

> Attackers can execute arbitrary OS commands via unauthenticated WebSocket terminal access in Eclipse Theia due to missing origin validation and authentication.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 3 Jul 2026
- **Updated:** 7 Jul 2026
- **Also known as:** GHSA-78g8-vm3p-97c6

## What is CVE-2026-10054?

CVE-2026-10054 is a high-severity missing authorization vulnerability in Eclipse Theia, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-1385 (Missing Origin Validation in WebSockets)

## Which versions are affected by CVE-2026-10054?


## How do I fix CVE-2026-10054?

No fix has been published for CVE-2026-10054 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10054 being exploited?

There is no known exploitation of CVE-2026-10054 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-10054 and fix it if it is affected.

What it is: CVE-2026-10054 is a high-severity missing authorization vulnerability in Eclipse Theia, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-10054 in the wild and no public exploit code.

Affected product: Eclipse Theia. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-10054/ (Markdown: https://insights.sbomify.com/CVE-2026-10054/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10054
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10054
- OSV: https://osv.dev/vulnerability/CVE-2026-10054

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10054/
Summaries are generated and may contain mistakes; the official description above is the record.