CVE-2026-61891

HIGH CVSS 3.1: 7.5 EPSS 0.45%
Updated Aug 07, 2026
In Eclipse
Parameter Value
CVSS 7.5 (HIGH)
Affected Versions before 1.74.0
Fixed In 1.74.0
Type CWE-36, CWE-200 (Information Exposure), CWE-306 (Missing Authentication for Critical Function), CWE-22 (Path Traversal)
Vendor In Eclipse
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Eclipse Theia
cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*
1.74.0