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Angular SSR: XSS via Unescaped Processing Instruction () Nodes 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 of `ProcessingInstruction` DOM nodes (``, `nodeType === 7`) when nested inside fallback raw-content elements (``). When rendered in a browser with scripting enabled, an unescaped closing tag sequence in a processing instruction prematurely closes the fallback raw-content tag and causes subsequent sibling elements to execute as live HTML. ### Technical Description In HTML5 parsing, fallback raw-content elements (``. ### Impact & Reachability * **Reachability**: Processing instruction nodes cannot be authored directly through standard Angular template syntax (which parses `` into comment nodes in DOM position). Reaching this vulnerability requires application or library code calling `inject(DOCUMENT).createProcessingInstruction(target, data)` or `Renderer2` DOM insertion methods with untrusted user input passed to `data` inside a fallback raw-content container. * **Impact**: In applications that programmatically construct processing instruction nodes inside fallback elements during server-side rendering, an attacker controlling the processing instruction data can break out of the container and execute arbitrary JavaScript in victims' browsers. ### Proof of Concept (Minimal Reproduction) ```ts import { Component, ElementRef, Renderer2, inject, DOCUMENT, AfterViewInit } from '@angular/core'; @Component({ selector: 'app-root', standalone: true, template: `` }

Announced Source revision 1
Original source ↗

GHSA-j3r3-mxqp-r2p4

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-j3r3-mxqp-r2p4

@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-j3r3-mxqp-r2p4/GHSA-j3r3-mxqp-r2p4.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-j3r3-mxqp-r2p4/GHSA-j3r3-mxqp-r2p4.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-j3r3-mxqp-r2p4/GHSA-j3r3-mxqp-r2p4.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-j3r3-mxqp-r2p4/GHSA-j3r3-mxqp-r2p4.json"
    }
  }
]
Related CVEs
CVE-2026-88058

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Event
#23641 · Revision 1
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Publisher date
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