# CVE-2026-61891

## Summary

- **CVE ID:** CVE-2026-61891
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
- **CWE:** CWE-22, CWE-36, CWE-200, CWE-306
- **Published:** Aug 5, 2026
- **Last Modified:** Aug 5, 2026

## Description

In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend exposes HTTP file-download endpoints (`GET /file`, `GET /files/`, `PUT /files/`) that convert a client-supplied URI directly to a filesystem path and stream the file, without confining it to the workspace or any allow-listed root. In browser (non-Electron) deployments the connection token is enforced only on WebSocket upgrades; the HTTP middleware in `@theia/core` re-issues the cookie and calls `next()` without rejecting tokenless HTTP requests, so these endpoints are reachable without a valid token. As a result an unauthenticated client can read any file readable by the backend process, including files outside the opened workspace (for example `/etc/hosts`, SSH keys, or tokens). Electron mode uses a separate `ElectronSecurityToken` and is not affected via this path.

## Affected Products

- Eclipse Foundation — Eclipse Theia (0)

## References

- [CNA](https://github.com/eclipse-theia/theia/security/advisories/GHSA-qqc8-9538-25v4)
- [CNA](https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/570)
- [CNA](https://gitlab.eclipse.org/security/cve-assignment/-/work_items/176)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.45%
- **EPSS Percentile:** 37.9

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