CVE-2026-50556

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).

Patched Versions

• 22.0.0-rc.2
• 21.2.16
• 20.3.24
• 19.2.25

Workarounds

If you cannot immediately update your dependencies, you can:

• Avoid binding user-controlled values inside <noscript> elements.
• Sanitize any user input placed inside <noscript> to explicitly strip closing </noscript> tags before passing it to the template.

This vulnerability allows an attacker to perform same-origin Cross-Site Scripting (XSS) attacks against any user visiting an SSR-rendered page that binds user-controlled data inside a <noscript> element. This can lead to session hijacking, credentials theft, unauthorized actions on behalf of users, and defacement.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

1. What is CVE-2026-50556? CVE-2026-50556 is a high-severity cross-site scripting (XSS) vulnerability in @angular/platform-server (npm), affecting versions >= 22.0.0-next.0, < 22.0.0-rc.2. It is fixed in 22.0.0-rc.2, 21.2.16, 20.3.24, 19.2.25. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which versions of @angular/platform-server are affected by CVE-2026-50556? @angular/platform-server (npm) versions >= 22.0.0-next.0, < 22.0.0-rc.2 is affected.
3. Is there a fix for CVE-2026-50556? Yes. CVE-2026-50556 is fixed in 22.0.0-rc.2, 21.2.16, 20.3.24, 19.2.25. Upgrade to this version or later.
4. Is CVE-2026-50556 exploitable, and should I be worried? Whether CVE-2026-50556 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-50556 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-50556?
   • Upgrade @angular/platform-server to 22.0.0-rc.2 or later
   • Upgrade @angular/platform-server to 21.2.16 or later
   • Upgrade @angular/platform-server to 20.3.24 or later
   • Upgrade @angular/platform-server to 19.2.25 or later