7.7

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

Deferred
Published 21-09-2026Last modified 24-09-2026

Vulnerability summary

CVE-2026-55105 is a high (CVSS 7.7) Cross-site Scripting vulnerability in laurent22 joplin. EPSS estimates a 0.50% chance of exploitation in the next 30 days, higher than 41.5% of scored vulnerabilities.

Overall risk
31/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.7/10
010
High · v3.1 (CVE.org)
EPSS score
0.50%
0%100%
Low · +0.17 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 21-09-2026
    PublishedVulnerability first disclosed.
  2. 24-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.50%

Chance of exploitation in the next 30 days

Percentile

42%

Versus all other CVEs

30-day change

Increase +0.17 pp

From 0.32% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Laurent221 product
  • joplin< 3.6.15 | ≥ 3.7.0, < 3.7.2

1 vendor · 1 product

References

3 links