GHSA-9272-WG2R-7XMX

Vulnerability from github – Published: 2026-08-28 17:32 – Updated: 2026-08-28 17:32
VLAI
Summary
Yamcs has DOM XSS in Extension Routing
Details

Attack type: Unauthenticated remote Impact: Execution of arbitrary JavaScript in a user’s browser. Affected components: extension.matcher.ts:12, extension.component.ts:40, app.component.ts:134.

Yamcs 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.

image

Steps to Reproduce: 1. Start a Yamcs instance. 2. Insert the following URL into the browser and press enter (change ‘myproject’ to the name of your instance):

http://localhost:8090/ext/img%20src%3Dx%20onerror%3Dalert%281%29?c=myproject
  1. You will receive an alert with the number ‘1’ in it.

Recommendations: 1. Use document.createElement instead of innerHTML in extension.component.ts. 2. Validate the extension against registered plugin IDs. 3. Enforce a strict custom-element-name regex before mounting.

Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.13.1"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.yamcs:yamcs-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.13.0"
            },
            {
              "fixed": "5.13.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.12.7"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.yamcs:yamcs-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.12.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55566"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T17:32:16Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "**Attack type**: Unauthenticated remote \n**Impact**: Execution of arbitrary JavaScript in a user\u2019s 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\u2019s 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 \u2018myproject\u2019 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 \u20181\u2019 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.",
  "id": "GHSA-9272-wg2r-7xmx",
  "modified": "2026-08-28T17:32:16Z",
  "published": "2026-08-28T17:32:16Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Yamcs has DOM XSS in Extension Routing"
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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