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Angular: SSR XSS via Unescaped Content Across DocumentFragment Boundaries in Fallback Raw-Content Elements

Type: advisorySource: OSV1 source record

### Summary An XSS vulnerability exists in `@angular/platform-server` during server-side rendering (SSR) HTML serialization when traversing ancestor tags across `` element boundaries. When an application renders untrusted user input within raw-text tags (``, `<style>`, `<script>`), comments, or text nodes inside a `<template>` that is nested within a fallback raw-content element (`<noscript>`, `<iframe>`, `<noembed>`, `<noframes>`), matching closing tags (e.g., `</noscript>`) are not escaped during HTML serialization. When rendered in a browser, this unescaped closing tag prematurely terminates the fallback container and executes trailing markup as active DOM elements. ### Technical Description In HTML5 parsing, fallback raw-content elements (`<noscript>`, `<iframe>`, `<noembed>`, `<noframes>`) place the browser's tokenizer into `RAWTEXT` mode. In this mode, inner content is parsed as literal text until an end tag matching the container tag name (e.g., `</noscript>`) is encountered. To prevent XSS breakout vectors during SSR serialization, the DOM serializer inspects a node's ancestors to escape any matching fallback closing tags (`</tag` -> `&lt;/tag`). However: 1. Per DOM specifications, the children of a `<template>` element reside in a separate `DocumentFragment` (`template.content`), whose own `parentNode` is `null`. 2. The serializer's ancestor traversal previously only inspected element nodes. When traversing upward from a node inside `template.content`, traversal term

Announced Group revision 1
Original source ↗

GHSA-v3p8-whq6-r5jg

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:GHSA-v3p8-whq6-r5jg

@angular/platform-server

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
22.1.4

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

@angular/platform-server

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
21.2.22

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

@angular/platform-server

Source reference: /affected/2/package/name

Affected versions
Not stated in this record
Fixed versions
20.3.30

Source reference: /affected/2/ranges

Prerequisites
Not stated in this record

@angular/platform-server

Source reference: /affected/3/package/name

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "22.0.0"
          },
          {
            "fixed": "22.1.4"
          }
        ]
      }
    ],
    "package": {
      "name": "@angular/platform-server",
      "purl": "pkg:npm/%40angular/platform-server",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-v3p8-whq6-r5jg/GHSA-v3p8-whq6-r5jg.json"
    }
  },
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "21.0.0"
          },
          {
            "fixed": "21.2.22"
          }
        ]
      }
    ],
    "package": {
      "name": "@angular/platform-server",
      "purl": "pkg:npm/%40angular/platform-server",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-v3p8-whq6-r5jg/GHSA-v3p8-whq6-r5jg.json"
    }
  },
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "20.0.0"
          },
          {
            "fixed": "20.3.30"
          }
        ]
      }
    ],
    "package": {
      "name": "@angular/platform-server",
      "purl": "pkg:npm/%40angular/platform-server",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-v3p8-whq6-r5jg/GHSA-v3p8-whq6-r5jg.json"
    }
  },
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "0"
          },
          {
            "last_affected": "19.2.25"
          }
        ]
      }
    ],
    "package": {
      "name": "@angular/platform-server",
      "purl": "pkg:npm/%40angular/platform-server",
      "ecosystem": "npm"
    },
    "database_specific": {
      "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-v3p8-whq6-r5jg/GHSA-v3p8-whq6-r5jg.json"
    }
  }
]
Related CVEs
CVE-2026-88060

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Event
#14930 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement

Revision history

  1. GHSA-v3p8-whq6-r5jg · Revision 1Source updated