{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "1.66.0"
              },
              {
                "fixed": "1.74.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "CPE_RANGE"
            ]
          },
          "events": [
            {
              "introduced": "969039fdc5c1fde46b49502bf4a36559c2e4b724"
            },
            {
              "fixed": "172494ea2564ca07690e230805861146007fae79"
            }
          ],
          "repo": "https://github.com/eclipse-theia/theia",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-qmm6-p8q4-2g48"
  ],
  "database_specific": {
    "cna_assigner": "eclipse",
    "cwe_ids": [
      "CWE-22"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12609.json"
  },
  "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.",
  "id": "CVE-2026-12609",
  "modified": "2026-08-12T03:51:25.637746681Z",
  "published": "2026-08-05T10:55:42.736Z",
  "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"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}