Vulnerability · Published Aug 5, 2026 · Assigned by eclipse
CVE-2026-12609
High 7.5
In plain English
A high-severity path traversal in Eclipse Theia from Eclipse Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.6% (higher than 77% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei.
Official description
In Eclipse Theia versions 1.66.0 and up until including 1.73.1, the `@theia/plugin-ext` backend exposes the `/hostedPlugin/:pluginId/:path(*)` HTTP endpoint, which resolves the requested file path with `path.resolve(localPath, filePath)` without verifying that the resolved path stays within the plugin's directory. An unauthenticated network attacker can send percent-encoded `../` sequences (`%2e%2e%2f`) that decode into the path parameter and escape the plugin directory, allowing arbitrary files readable by the Theia backend process to be retrieved. Plugin IDs are derived deterministically from a plugin's publisher and name, so built-in plugins serve as reliable anchors that require no prior knowledge of the target system.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Eclipse Foundation | Eclipse Theia | 1.66.0 – before 1.74.0 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N