CVE-2026-22810

A path traversal vulnerability in the OneNote importer allows overwriting arbitrary files on disk.

Details

The OneNote converter does not sanitize the names of embedded files before writing them to disk. As a result, it's possible for an attacker to create a malicious .one file that includes file names containing ../../, that are then interpreted as part of the target path when extracting attachments from the .one file.

One affected location is embedded_file.rs, which generates a file name from a string previously parsed from the .one file,
https://github.com/laurent22/joplin/blob/af5108d70233b1db9410346958c1587cf7c1b16d/packages/onenote-converter/renderer/src/page/embedded_file.rs#L13-L16

Above, determine_filename passes through the provided file name.

Similar logic has been present since 4d7fa5972fe2986eae14cbf3a2801835cbe1384e (Joplin 3.2.2), when the OneNote importer was first introduced.

PoC

Screencast from 2025-11-20 13-50-21.webm

1. Import poc_v2.zip.
2. Open the application's profile directory, then open log.txt.
3. Observe that log.txt has been overwritten non-log-file content (a WAV file).

Tested on Fedora Linux 43 with Joplin 3.4.12 (prod, linux) and Joplin 3.5.6 (dev, linux).

Note: The PoC ZIP file overwrites Joplin's log.txt. It is also possible to craft a file that overwrites more sensitive system files (e.g. .bashrc on Linux).

Patched in

• Joplin: https://github.com/laurent22/joplin/commit/791668455e1aae50501ff57ea4783b3fba9d377c
• one2html: https://github.com/msiemens/one2html/commit/948d65cdca5bb35d776b8b235ec05ff15249fd41

This is a path traversal vulnerability that impacts all versions of Joplin (<= v3.5.6) that include a OneNote importer. Importing a crafted OneNote export file allows an attacker to overwrite arbitrary files, potentially leading to remote code execution.

CVE-2026-22810 has a CVSS score of 8.2 (High). The vector is requires local access, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.5.7); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-22810? CVE-2026-22810 is a high-severity security vulnerability in @joplin/onenote-converter (npm), affecting versions < 3.5.7. It is fixed in 3.5.7.
2. How severe is CVE-2026-22810? CVE-2026-22810 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @joplin/onenote-converter are affected by CVE-2026-22810? @joplin/onenote-converter (npm) versions < 3.5.7 is affected.
4. Is there a fix for CVE-2026-22810? Yes. CVE-2026-22810 is fixed in 3.5.7. Upgrade to this version or later.
5. Is CVE-2026-22810 exploitable, and should I be worried? Whether CVE-2026-22810 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-22810 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-22810? Upgrade @joplin/onenote-converter to 3.5.7 or later.