Angular: SSR XSS via Unescaped <template> Content Across DocumentFragment Boundaries in Fallback Raw-Content Elements
Published Sep 10, 2026 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
Angular: SSR XSS via Unescaped <template> Content Across DocumentFragment Boundaries in Fallback Raw-Content Elements
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
An XSS vulnerability exists in @angular/platform-server during server-side rendering (SSR) HTML serialization when traversing ancestor tags across <template> element boundaries. When an application renders untrusted user input within raw-text tags (<xmp>, <style>, <script>), comments, or text nodes inside a <template> that is nested within a fallback raw-content element (<noscript>, <iframe>, <noembed>, <noframes>), matching closing tags (e.g., </noscript>) are not escaped during HTML serialization. When rendered in a browser, this unescaped closing tag prematurely terminates the fallback container and executes trailing markup as active DOM elements.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- LOW
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
- Security advisory ↗
- Patch commit ↗
- Patch commit ↗
- Patch commit ↗
- Patch commit ↗
- Source repository ↗
- Source repository ↗
- Source repository ↗
Record history
Published Sep 10, 2026 · Last refreshed Nov 3, 2026