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CVE-2026-12609

In Eclipse Theia versions 1.66.0 and up until including 1.73.1, the `@theia/plugin-ext` backend exposes the `/hostedPlugin/:pluginId/:path(*

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.74.0
1 Nuclei template
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • Eclipse Foundation Eclipse Theia

    From 1.66.0 · fixed in 1.74.0

References 4

GitHub · eclipse-theia/theia

gitlab.eclipse.org

GitHub · projectdiscovery/nuclei-templates