CVE-2026-50556
Fix: angular/domino#29CVE-2026-50556 is a Cross-site Scripting (XSS) vulnerability in @angular/platform-server. O3 Security confirms whether CVE-2026-50556 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Angular: Missing `<noscript>` Raw-Text Serialization Escaping leads to Cross-Site Scripting (XSS) in Angular SSR
Real-World Exposure
@angular/platform-server📦@angular/platform-server📦@angular/platform-server📦@angular/platform-server📦@angular/platform-serverReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 22.0.0-rc.2, 21.2.16, 20.3.24, and 19.2.25, a Cross-Site Scripting (XSS) vulnerability exists in @angular/platform-server's DOM emulation dependency (domino) when serializing the content of <noscript> elements. When 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. However, 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. The 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). This vulnerability is fixed in 22.0.0-rc.2, 21.2.16, 20.3.24, and 19.2.25.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @angular/platform-server | ≥ 22.0.0-next.0&&< 22.0.0-rc.2 | 22.0.0-rc.2 |
| 📦npm | @angular/platform-server | ≥ 21.0.0-next.0&&< 21.2.16 | 21.2.16 |
| 📦npm | @angular/platform-server | ≥ 20.0.0-next.0&&< 20.3.24 | 20.3.24 |
| 📦npm | @angular/platform-server | ≥ 19.0.0-next.0&&< 19.2.25 | 19.2.25 |
| 📦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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @angular/platform-server to 22.0.0-rc.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-50556 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-50556 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-50556. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-50556 in your dependencies?
O3 detects CVE-2026-50556 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.