{"id":"GHSA-9272-wg2r-7xmx","summary":"Yamcs has DOM XSS in Extension Routing","details":"**Attack type**: Unauthenticated remote \n**Impact**: Execution of arbitrary JavaScript in a user’s browser.\n**Affected components**: extension.matcher.ts:12, extension.component.ts:40, app.component.ts:134.\n\nYamcs is vulnerable to cross-site scripting in the /ext URL endpoint. By inputting specially crafted code into the URL, an attacker can execute arbitrary JavaScript code in a user’s browser. This URL may be sent to a user via a phishing email.\n \n\u003cimg width=\"940\" height=\"294\" alt=\"image\" src=\"https://github.com/user-attachments/assets/d886d65c-9bb5-4599-ac11-55db83aafc0e\" /\u003e\n\nSteps to Reproduce:\n1.\tStart a Yamcs instance.\n2.\tInsert the following URL into the browser and press enter (change ‘myproject’ to the name of your instance):\n```\nhttp://localhost:8090/ext/img%20src%3Dx%20onerror%3Dalert%281%29?c=myproject\n```\n3.\tYou will receive an alert with the number ‘1’ in it.\n\nRecommendations:\n1.\tUse document.createElement instead of innerHTML in extension.component.ts.\n2.\tValidate the extension against registered plugin IDs.\n3.\tEnforce a strict custom-element-name regex before mounting.","aliases":["CVE-2026-55566"],"modified":"2026-08-28T17:56:00.784762Z","published":"2026-08-28T17:32:16Z","database_specific":{"github_reviewed_at":"2026-08-28T17:32:16Z","nvd_published_at":null,"cwe_ids":["CWE-79"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/yamcs/yamcs/security/advisories/GHSA-9272-wg2r-7xmx"},{"type":"WEB","url":"https://github.com/yamcs/yamcs/commit/8e18e279d8ce761c21f4f67bbd06a1bff804d297"},{"type":"WEB","url":"https://github.com/yamcs/yamcs/commit/ecf34a4e2ccbe085e6ceff0253595b24d5ecb4aa"},{"type":"PACKAGE","url":"https://github.com/yamcs/yamcs"},{"type":"WEB","url":"https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8"},{"type":"WEB","url":"https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2"}],"affected":[{"package":{"name":"org.yamcs:yamcs-core","ecosystem":"Maven","purl":"pkg:maven/org.yamcs/yamcs-core"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.13.0"},{"fixed":"5.13.2"}]}],"versions":["5.13.0","5.13.1"],"database_specific":{"last_known_affected_version_range":"\u003c= 5.13.1","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-9272-wg2r-7xmx/GHSA-9272-wg2r-7xmx.json"}},{"package":{"name":"org.yamcs:yamcs-core","ecosystem":"Maven","purl":"pkg:maven/org.yamcs/yamcs-core"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.12.8"}]}],"versions":["0.29.3","0.30.0","3.0.0","3.1.0","3.1.1","3.1.2","3.2.0","3.2.1","3.2.2","3.3.0","3.3.1","3.4.0","3.4.1","3.4.11","3.4.2","3.4.3","3.4.4","3.4.5","3.4.6","3.4.8","4.0.0","4.0.1","4.1.1","4.1.2","4.10.0","4.10.1","4.10.2","4.10.3","4.10.4","4.10.5","4.10.6","4.10.7","4.10.8","4.10.9","4.2.0","4.2.1","4.2.2","4.3.0","4.3.1","4.4.0","4.4.1","4.4.2","4.5.0","4.6.0","4.6.1","4.6.2","4.6.3","4.7","4.7.1","4.7.3","4.8.0","4.8.1","4.9.0","4.9.1","4.9.2","4.9.3","4.9.4","5.0.0","5.1.0","5.1.1","5.1.2","5.1.3","5.1.4","5.10.0","5.10.1","5.10.10","5.10.11","5.10.12","5.10.2","5.10.3","5.10.4","5.10.5","5.10.6","5.10.7","5.10.8","5.10.9","5.11.0","5.11.1","5.11.10","5.11.11","5.11.12","5.11.13","5.11.2","5.11.3","5.11.4","5.11.5","5.11.6","5.11.7","5.11.8","5.11.9","5.12.0","5.12.1","5.12.2","5.12.3","5.12.4","5.12.5","5.12.6","5.12.7","5.2.0","5.2.1","5.2.2","5.2.3","5.2.4","5.2.5","5.2.6","5.3.0","5.3.1","5.3.2","5.3.3","5.3.4","5.3.5","5.3.6","5.4.0","5.4.1","5.4.2","5.4.3","5.4.4","5.4.5","5.5.0","5.5.1","5.5.2","5.5.3","5.5.4","5.5.5","5.5.6","5.5.7","5.6.0","5.6.1","5.6.2","5.7.0","5.7.1","5.7.10","5.7.11","5.7.12","5.7.13","5.7.2","5.7.3","5.7.4","5.7.5","5.7.6","5.7.7","5.7.8","5.7.9","5.8.0","5.8.1","5.8.2","5.8.3","5.8.4","5.8.5","5.8.6","5.8.7","5.8.8","5.9.0","5.9.1","5.9.10","5.9.11","5.9.12","5.9.2","5.9.3","5.9.4","5.9.5","5.9.6","5.9.7","5.9.8","5.9.8.1","5.9.9"],"database_specific":{"last_known_affected_version_range":"\u003c= 5.12.7","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-9272-wg2r-7xmx/GHSA-9272-wg2r-7xmx.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N"}]}