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Angular SSR: Denial of Service (DoS) via Infinite Loop on Malformed DOCTYPE

Type: advisorySource: OSV1 source record

A Denial of Service (DoS) vulnerability exists in `@angular/platform-server`'s DOM emulation parser (`domino`). When processing untrusted user input containing an incomplete DOCTYPE declaration ending with whitespace before EOF (such as ``, and keyword matching advance `nextchar`, the EOF branch (`case -1: // EOF`) emitted doctype and EOF tokens without advancing `nextchar` or transitioning out of the state: ```javascript case -1: // EOF forcequirks(); emitDoctype(); emitEOF(); break; ``` Because `nextchar` remained unchanged pointing to the EOF marker character (`\uFFFF`), the scanner loop (`while (nextchar < numchars)`) repeatedly re-invoked `after_doctype_name_state` with `codepoint = EOF` indefinitely. In Node.js's single-threaded runtime, this synchronous loop starves the event loop entirely. ### Impact & Reachability * **Reachability**: The vulnerability is reachable in any Angular SSR application where untrusted user input is bound to `[innerHTML]`, interpolated into markup, or sanitized on the server. * **Impact**: Successful exploitation allows an unauthenticated remote attacker to cause an immediate Denial of Service (DoS) by sending a payload containing an incomplete DOCTYPE (e.g., ``, }) export class AppComponent { // Attacker-controlled input containing an incomplete DOCTYPE ending with whitespace payload = '

Announced Source revision 1
Original source ↗

GHSA-f67j-2jqw-jpq7

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-f67j-2jqw-jpq7

@angular/platform-server

Source reference: /affected/0/package/name

Affected versions
Not stated in this record
Fixed versions
22.1.6

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
21.2.23

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
20.3.31

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": "22.1.6"
          }
        ]
      }
    ],
    "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-f67j-2jqw-jpq7/GHSA-f67j-2jqw-jpq7.json"
    }
  },
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "21.0.0"
          },
          {
            "fixed": "21.2.23"
          }
        ]
      }
    ],
    "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-f67j-2jqw-jpq7/GHSA-f67j-2jqw-jpq7.json"
    }
  },
  {
    "ranges": [
      {
        "type": "SEMVER",
        "events": [
          {
            "introduced": "20.0.0"
          },
          {
            "fixed": "20.3.31"
          }
        ]
      }
    ],
    "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-f67j-2jqw-jpq7/GHSA-f67j-2jqw-jpq7.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-f67j-2jqw-jpq7/GHSA-f67j-2jqw-jpq7.json"
    }
  }
]
Related CVEs
CVE-2026-101895

Source reference: /aliases

Publisher severity

high

Source reference: /database_specific/severity

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-101895 · High

angular, platform-server

Event
#23693 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement