CVE-2026-50556: @angular/platform-server Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gxx4-3xcv-f8qx",
  "modified" : "2026-06-15T17:21:03Z",
  "published" : "2026-06-15T17:21:03Z",
  "aliases" : [ "CVE-2026-50556" ],
  "summary" : "@angular/platform-server: Missing `<noscript>` Raw-Text Serialization Escaping leads to Cross-Site Scripting (XSS) in Angular SSR",
  "details" : "A Cross-Site Scripting (XSS) vulnerability exists in `@angular/platform-server`'s DOM emulation dependency (`domino`) when serializing the content of `<noscript>` elements.\n\nWhen rendering dynamic text content inside a `<noscript>` element via template bindings (such as `{{ value }}` or `[textContent]`), the template engine expects the browser to render the content safely. Under Server-Side Rendering (SSR), `domino` is configured with scripting enabled, meaning `<noscript>` is treated as a raw-text element.\n\nHowever, `domino`'s serializer completely omitted `<noscript>` from the list of raw-text elements requiring closing-tag escaping during DOM serialization. As a result, any occurrence of `</noscript>` in the bound dynamic text was **never escaped under any circumstances**.\n\nThe unescaped closing tag was serialized directly into the output HTML (e.g. `<noscript></noscript><script>alert(1)</script></noscript>`). When parsed by a browser, it closes the `<noscript>` block early, allowing the injected `<script>` block to execute in the user's browser context, causing same-origin Cross-Site Scripting (XSS).\n\n### Impact\n\nThis vulnerability allows an attacker to perform same-origin Cross-Site Scripting (XSS) attacks against any user visiting an SSR-rendered page that binds user-controlled data inside a `<noscript>` element. This can lead to session hijacking, credentials theft, unauthorized actions on behalf of users, and defacement.\n\n### Patched Versions\n\n- 22.0.0-rc.2\n- 21.2.16\n- 20.3.24\n- 19.2.25\n\n### Workarounds\n\nIf you cannot immediately update your dependencies, you can:\n\n- Avoid binding user-controlled values inside `<noscript>` elements.\n- Sanitize any user input placed inside `<noscript>` to explicitly strip closing `</noscript>` tags before passing it to the template.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "22.0.0-next.0"
      }, {
        "fixed" : "22.0.0-rc.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "21.0.0-next.0"
      }, {
        "fixed" : "21.2.16"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "20.0.0-next.0"
      }, {
        "fixed" : "20.3.24"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "19.0.0-next.0"
      }, {
        "fixed" : "19.2.25"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@angular/platform-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "18.2.14"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/security/advisories/GHSA-gxx4-3xcv-f8qx"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/angular/issues/68903"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/angular/domino/pull/29"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/angular/angular"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-15T17:21:03Z",
    "nvd_published_at" : null
  }
}