CVE-2026-34600
CWE-200Published: May 19, 2026· Updated: May 20, 2026
Official 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.
Technical Analysis
CVE-2026-34600 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 5.7.
From a weakness classification perspective (CWE-200): Information exposure vulnerabilities leak sensitive data to unauthorized actors.
CVSS v3.1 Vector Breakdown
Exploit & PoC Resources
All References (4)
Quick Facts
Related CVEs (CWE-200)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-34600 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts