# CVE-2026-79320: Cross-site scripting in n/a

> Attacker can execute arbitrary scripts in the application origin via DOM-based XSS in Stencil core when experimental slot fixes are enabled.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 21 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-pm76-9f64-vwpc

## What is CVE-2026-79320?

CVE-2026-79320 is a medium-severity cross-site scripting vulnerability in n/a, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-79320?


## How do I fix CVE-2026-79320?

No fix has been published for CVE-2026-79320 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-79320 being exploited?

There is no known exploitation of CVE-2026-79320 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79320 and fix it if it is affected.

What it is: CVE-2026-79320 is a medium-severity cross-site scripting vulnerability in n/a, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-79320 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-79320/ (Markdown: https://insights.sbomify.com/CVE-2026-79320/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79320
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79320
- OSV: https://osv.dev/vulnerability/CVE-2026-79320

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-79320/
Summaries are generated and may contain mistakes; the official description above is the record.