CVE-2026-61891

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-08-05 12:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-24 16:10 UTC Last updatedMost recent change to the record

Details

Published

2026-08-05 12:18 UTC

Last modified

2026-10-24 16:10 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Analyzed

Affected

• Eclipse Theia < 1.74.0

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None