CVE-2026-34600: Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Versions 3.5.2 and prior contain a logic err...

Description

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Versions 3.5.2 and prior contain a logic error in the delta API that allows share recipients to download notes that are no longer shared with them, related to but not fully fixed by the prior patch in #14289. In ChangeModel.delta, when DELTA_INCLUDES_ITEMS is enabled (the default), the latest state of items is attached to delta output without verifying that those items are still shared with the requesting user, and the existing removal logic only filters items deleted for all users. Additionally, the change compression logic incorrectly reduces create - delete to NOOP, which is unsafe because compression is applied per page and an item can have multiple create events; if an earlier create falls on a separate page from a later create -> delete pair, the deletion is dropped and the sequence collapses to a create. As a result, the delta API returns a create event for a deleted item with the full latest content attached, exposing notes the user no longer has access to. This issue has been fixed in version 3.5.3.

Metrics

CVSS 3.1

5.7/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

EPSS Probability

0.27%

18.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published: May 19, 2026
Last Modified: Jul 24, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-34600?

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Versions 3.5.2 and prior contain a logic error in the delta API that allows share recipients to download notes that are no longer shared with them, related to but not fully fixed by the prior patch in #14289. In ChangeModel.delta, when DELTA_INCLUDES_ITEMS is enabled (the default), the latest state of items is attached to delta output without verifying that those items are still shared with the requesting user, and the existing removal logic only filters items deleted for all users. Additionally, the change compression logic incorrectly reduces create - delete to NOOP, which is unsafe because compression is applied per page and an item can have multiple create events; if an earlier create falls on a separate page from a later create -> delete pair, the deletion is dropped and the sequence collapses to a create. As a result, the delta API returns a create event for a deleted item with the full latest content attached, exposing notes the user no longer has access to. This issue has been fixed in version 3.5.3.

How severe is CVE-2026-34600?

CVE-2026-34600 has a CVSS score of 5.7/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2026-34600?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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