{
"id": "GHSA-9272-wg2r-7xmx",
"aliases": [
"CVE-2026-55566"
],
"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<img width=\"940\" height=\"294\" alt=\"image\" src=\"https://github.com/user-attachments/assets/d886d65c-9bb5-4599-ac11-55db83aafc0e\" />\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.",
"summary": "Yamcs has DOM XSS in Extension Routing",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.13.0"
},
{
"fixed": "5.13.2"
}
]
}
],
"package": {
"name": "org.yamcs:yamcs-core",
"ecosystem": "Maven"
},
"database_specific": {
"last_known_affected_version_range": "<= 5.13.1"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.12.8"
}
]
}
],
"package": {
"name": "org.yamcs:yamcs-core",
"ecosystem": "Maven"
},
"database_specific": {
"last_known_affected_version_range": "<= 5.12.7"
}
}
],
"modified": "2026-08-28T17:32:16Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N"
}
],
"published": "2026-08-28T17:32:16Z",
"references": [
{
"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": "WEB"
},
{
"url": "https://github.com/yamcs/yamcs",
"type": "PACKAGE"
},
{
"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",
"type": "WEB"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": null,
"github_reviewed_at": "2026-08-28T17:32:16Z"
}
}