CVE-2026-34571: CI4MS Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fc4p-p49v-r948",
  "modified" : "2026-04-06T17:15:59Z",
  "published" : "2026-04-01T22:09:03Z",
  "aliases" : [ "CVE-2026-34571" ],
  "summary" : "CI4MS: Stored Cross‑Site Scripting (Stored XSS) in Backend User Management Allows Session Hijacking and Full Administrative Account Compromise",
  "details" : "### Summary\n\nA critical Stored Cross-Site Scripting (Stored XSS) vulnerability exists in the backend user management functionality. The application fails to properly sanitize user-controlled input before rendering it in the administrative interface, allowing attackers to inject persistent JavaScript code. This results in automatic execution whenever backend users access the affected page, enabling session hijacking, privilege escalation, and full administrative account compromise.\n\n---\n\n### Details\n\nThe vulnerability resides in the backend user creation feature accessible via:\n\n```\n/backend/users\n```\n\nUser-supplied input in the **name** and **surname** fields is stored without proper validation or sanitization. When this data is later rendered in the backend users listing page, it is injected directly into the HTML without output encoding.\n\nBecause of this, attackers can embed malicious JavaScript payloads that execute in the context of authenticated backend users.\n\nThis indicates missing contextual output escaping (e.g., HTML encoding) and insufficient input sanitization, leading to persistent script execution.\n\nThe vulnerability is particularly severe because:\n\n* The payload is stored in the database (persistent XSS).\n* The script executes automatically on page load.\n* The affected page appears to be an administrative/backend interface, increasing the risk of privilege escalation.\n\n---\n\n### PoC\n\nSteps to reproduce:\n\n1. Navigate to:\n\n```\nhttp://localhost:8080/backend/users\n```\n\n2. Click **Add New User**.\n\n3. Create a new user.\n\n4. In the **name** and **surname** fields, insert the following payload:\n\n```\nadnan\"><img src=1 onerror=alert(document.cookie)><<e>img src=1 onerror=alert(document.cookie)>\n```\n\n5. Save the user.\n\n6. After saving, a popup displaying cookies will appear, demonstrating JavaScript execution.\n\n7. Revisit:\n\n```\nhttp://localhost:8080/backend/users\n```\n\n8. The popup automatically triggers again, confirming that the malicious script is stored and executed persistently.\n<img width=\"1534\" height=\"834\" alt=\"image\" src=\"https://github.com/user-attachments/assets/83f3d124-cf2e-472d-87cc-8c668ea81cba\" />\n\n---\n\n### Impact\n\nSeverity: **Critical**\n\nThis vulnerability enables:\n\n* Persistent execution of attacker-controlled JavaScript in privileged backend contexts.\n* Theft of session cookies, potentially leading to full account takeover.\n* Unauthorized actions performed on behalf of administrators (CSRF-like behavior via XSS).\n* Privilege escalation if a high-privilege user views the page.\n* Injection of keyloggers, credential harvesting scripts, or malicious redirects.\n* Full compromise of backend administrative functionality depending on role permissions.\n\nSince the payload executes automatically without user interaction once stored, exploitation requires minimal effort and can impact all backend users.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "ci4-cms-erp/ci4ms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.31.0.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.28.6.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-fc4p-p49v-r948"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34571"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ci4-cms-erp/ci4ms"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ci4-cms-erp/ci4ms/releases/tag/0.31.0.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T22:09:03Z",
    "nvd_published_at" : "2026-04-01T22:16:21Z"
  }
}