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CVE-2026-55105

7.7 · HIGH

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks.

Published Sep 21, 2026CWE-79EPSS 0.50%

Overview

CVE-2026-55105 is a high-severity vulnerability. It was published on September 21, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/laurent22/joplin/commit/8e0812de9d79d1f0698bb76a8c5d7e991df9748dGitHubgithub.com/laurent22/joplin/pull/15659GitHubgithub.com/laurent22/joplin/security/advisories/GHSA-f7q3-3grx-6wg9GitHubgithub.com/laurent22/joplin/security/advisories/GHSA-f7q3-3grx-6wg9

How CyberStrike helps

Frequently asked questions

What is CVE-2026-55105?

CVE-2026-55105 is a high-severity vulnerability. It was published on September 21, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

How severe is CVE-2026-55105?

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-55105?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-55105?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-55105 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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