CVE-2026-101895 — @angular/platform-server
Fix: angular/angular@3db26e2CVE-2026-101895 is a Uncontrolled Resource Consumption vulnerability in @angular/platform-server. A fix is available for @angular/platform-server — see the affected versions and patch details below.
Angular SSR: Denial of Service (DoS) via Infinite Loop on Malformed DOCTYPE
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-101895.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@angular/platform-servernpmDescription
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 <!DOCTYPE html ), the HTML parser enters an infinite synchronous loop, pegging CPU utilization at 100% and completely freezing the Node.js server process.
Technical Description
In Angular Server-Side Rendering (SSR), @angular/platform-server uses domino to parse and sanitize HTML bound through template bindings (such as [innerHTML]) or manipulated via DOM APIs.
In Domino's HTML parser (lib/HTMLParser.js), tokenizer states that specify fixed lookahead—such as after_doctype_name_state (lookahead = 6)—rely on the state handler function to explicitly advance the character index pointer (nextchar). While branches for whitespace, >, 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:
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.,
<!DOCTYPE html). The Node.js SSR process locks up at 100% CPU and ceases responding to all concurrent and subsequent HTTP requests.
Proof of Concept:
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
standalone: true,
template: `<div [innerHTML]="payload"></div>`,
})
export class AppComponent {
// Attacker-controlled input containing an incomplete DOCTYPE ending with whitespace
payload = '<!DOCTYPE html ';
}
Workarounds
- Avoid binding untrusted user input directly to
[innerHTML]in server-rendered templates; use standard text interpolation ({{ userInput }}) or[textContent]when raw HTML rendering is not required. - Validate or sanitize user input before passing it to
[innerHTML]on the server by stripping or rejecting strings matching/^<!DOCTYPE/i.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @angular/platform-server | ≥ 22.0.0&&< 22.1.6 | 22.1.6npm install @angular/platform-server@22.1.6 |
| 📦npm | @angular/platform-server | ≥ 21.0.0&&< 21.2.23 | 21.2.23npm install @angular/platform-server@21.2.23 |
| 📦npm | @angular/platform-server | ≥ 20.0.0&&< 20.3.31 | 20.3.31npm install @angular/platform-server@20.3.31 |
| 📦npm | @angular/platform-server | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @angular/platform-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @angular/platform-server to 22.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-101895 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-101895 in your dependencies?
Find it across npm, including transitive dependencies.