CVE-2026-10055 Server-side request forgery in Eclipse Theia
Remote attackers can exploit an unvalidated URL in Eclipse Theia to perform server-side requests and read internal responses, exposing sensitive backend data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-10055?
CVE-2026-10055 is a high-severity server-side request forgery vulnerability in Eclipse Theia, published on 3 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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).
Which versions are affected by CVE-2026-10055?
How do I fix CVE-2026-10055?
No fix has been published for CVE-2026-10055 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-10055 being exploited?
There is no known exploitation of CVE-2026-10055 in the wild and no public exploit code.
Sources
Also known as GHSA-2m57-xxmh-v696.