laurent22 joplin up to 3.5.2 Delta API ChangeModel.delta permissions

Summaryinfo

A vulnerability classified as critical was found in laurent22 joplin up to 3.5.2. The impacted element is the function ChangeModel.delta of the component Delta API. Executing a manipulation can lead to permissions. This vulnerability is handled as CVE-2026-34600. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in laurent22 joplin up to 3.5.2 and classified as critical. This vulnerability affects the function ChangeModel.delta of the component Delta API. The manipulation with an unknown input leads to a permissions vulnerability. The CWE definition for the vulnerability is CWE-281. The product does not preserve permissions or incorrectly preserves permissions when copying, restoring, or sharing objects, which can cause them to have less restrictive permissions than intended. As an impact it is known to affect confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-34600 since 03/30/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1222.

Upgrading to version 3.5.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• laurent22

Name

• joplin

Version

• 3.5.0
• 3.5.1
• 3.5.2

Website

• Product: https://github.com/laurent22/joplin/

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