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
eclipse: theia
References3
- gitlab.eclipse.org/security/cve-assignment/-/work_items/133 Vendor Advisory
- gitlab.eclipse.org/security/vulnerability-reports/-/issues/524 Issue TrackingMitigationVendor Advisory
- github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8… Broken Link
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - EPSS — exploit probability
- 2% percentile: 77 · as of 13 November 2026
- CWE
- CWE-22
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