Theia 1.26.0 - RPC /services/request-service Open Proxy via Server-side HTTP
CVE-2026-10055 Published on July 3, 2026

In Eclipse Theia since version 1.26.0, the backend /services/request-service RPC accepts an attacker-controlled URL from any client connected to the standard /services messaging endpoint, performs the HTTP request server-side, and returns the full response body to the caller. Because the destination URL is neither validated nor allowlisted, a remote attacker with access to the Theia service connection can issue server-side HTTP requests to localhost or other backend-reachable hosts and read their responses, exposing internal administrative endpoints, cloud instance metadata services, and other resources that are intentionally outside the browser network boundary. The vulnerability affects deployments where the Theia service connection is reachable by untrusted users (for example, multi-tenant or publicly-reachable Theia deployments).

NVD

Vulnerability Analysis

CVE-2026-10055 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
LOW
Availability Impact:
NONE

Weakness Types

What is a SSRF Vulnerability?

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.

CVE-2026-10055 has been classified to as a SSRF vulnerability or weakness.

What is an Information Disclosure Vulnerability?

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

CVE-2026-10055 has been classified to as an Information Disclosure vulnerability or weakness.


Products Associated with CVE-2026-10055

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Eclipse Theia
 

Affected Versions

Eclipse Foundation Eclipse Theia: