{"id":"CVE-2026-12609","details":"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.","aliases":["GHSA-qmm6-p8q4-2g48"],"modified":"2026-08-12T03:51:25.637746681Z","published":"2026-08-05T10:55:42.736Z","database_specific":{"cwe_ids":["CWE-22"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12609.json","cna_assigner":"eclipse"},"references":[{"type":"WEB","url":"https://gitlab.eclipse.org/security/cve-assignment/-/work_items/133"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12609.json"},{"type":"ADVISORY","url":"https://github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8q4-2g48"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-12609"},{"type":"REPORT","url":"https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/524"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/eclipse-theia/theia","events":[{"introduced":"969039fdc5c1fde46b49502bf4a36559c2e4b724"},{"fixed":"172494ea2564ca07690e230805861146007fae79"}],"database_specific":{"cpe":"cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"1.66.0"},{"fixed":"1.74.0"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v1.73.0","v1.72.0","next","v1.71.0","v1.70.0","v1.69.0","v1.68.0","v1.67.0","v1.66.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-12609.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}