# GHSA-97r8-rf7q-wmjw: Sveltia CMS: Stored XSS in entry summary rendering via entity-decoded HTML

> Stored XSS in Sveltia CMS allows attackers to execute arbitrary JavaScript in the browser of users viewing entry summaries.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 May 2026

## What is GHSA-97r8-rf7q-wmjw?

GHSA-97r8-rf7q-wmjw is a cross-site scripting vulnerability in @sveltia/cms, published on 18 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

### Impact

A stored cross-site scripting (XSS) vulnerability affected entry summary rendering in Sveltia CMS.

Entry summaries that allowed limited Markdown were parsed, sanitized, and then HTML entities were decoded. This order allowed specially crafted entity-encoded HTML, such as encoded tags or event handler attributes, to become active HTML after sanitization. When the resulting summary was rendered in the CMS UI, arbitrary JavaScript could execute in the browser of a user viewing the affected entry list or search result.

The practical impact is limited in currently supported Sveltia CMS usage because the CMS is intended for a single developer or a small trusted team, and [open authoring](https://sveltiacms.app/en/docs/workflows/open) / untrusted multi-user authoring is not currently implemented. Exploitation requires the ability to place malicious content into the repository or content source that the CMS loads.

### Patches

The issue has been patched by changing entry summary sanitization so that HTML entity decoding happens before sanitization for Markdown-enabled summaries. This ensures any decoded HTML is processed by the sanitizer before being rendered.

Users should upgrade to Sveltia CMS [v0.160.1](https://github.com/sveltia/sveltia-cms/releases/tag/v0.160.1) or later.

### Workarounds

If upgrading is not immediately possible, avoid loading CMS content from untrusted authors and review content for entity-encoded HTML payloads in fields used by entry summaries.

Administrators can also reduce exposure by avoiding Markdown-enabled summary rendering for untrusted content where possible, or by ensuring repository write access is limited to trusted users only.

### Resources

- CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- https://cwe.mitre.org/data/definitions/79.html

## Which versions are affected by GHSA-97r8-rf7q-wmjw?

2 open source packages ship an affected version, including @sveltia/cms.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@sveltia/cms` | npm | All versions | 0.160.1 |
| `@sveltia/cms` | npm | All versions | 0.160.1 |

## How do I fix GHSA-97r8-rf7q-wmjw?

Upgrade @sveltia/cms to 0.160.1 or later.

## Is GHSA-97r8-rf7q-wmjw being exploited?

There is no known exploitation of GHSA-97r8-rf7q-wmjw in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-97r8-rf7q-wmjw and fix it if it is affected.

What it is: GHSA-97r8-rf7q-wmjw is a cross-site scripting vulnerability in @sveltia/cms, published on 18 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of GHSA-97r8-rf7q-wmjw in the wild and no public exploit code.

Affected packages and fixed versions:
- @sveltia/cms (npm): affected all versions; fixed in 0.160.1
- @sveltia/cms (npm): affected all versions; fixed in 0.160.1

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/GHSA-97r8-rf7q-wmjw/ (Markdown: https://insights.sbomify.com/GHSA-97r8-rf7q-wmjw/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-97r8-rf7q-wmjw

---
From sbomify Insights: https://insights.sbomify.com/GHSA-97r8-rf7q-wmjw/
Summaries are generated and may contain mistakes; the official description above is the record.