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(*) HTTP endpoint,...
- Published
- Aug 5, 2026
- Updated
- Aug 5, 2026
- Assigning CNA
- eclipse
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NLow · next 30 days
- Percentile
- 42.7%
- Model date
- Oct 11, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
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.
Sources
http/cves/2026/CVE-2026-12609.yaml
Nuclei TemplatesDeclared conditions
- network: http($.protocol_keys)
- verification: dsl($.matchers[*].type)
Responsible use
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