CVE-2026-12609 (GCVE-0-2026-12609)

Vulnerability from cvelistv5 – Published: 2026-08-05 10:55 – Updated: 2026-08-05 13:03
VLAI
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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-05 13:03 UTC
CWE
Assigner
eclipse CNA under the mitre root
CNA scorecard C 66/100 over 204 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Eclipse Foundation Eclipse Theia Affected: 1.66.0 , < 1.74.0 (semver)
guessed Create a notification for this product.
Credits
http://github.com/geo-chen
Show details on NVD website
To clipboard 

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