SB2026052626 - Improper access control in Joplin Server

Description

This security bulletin contains information about 1 vulnerability.

1) Improper access control (CVE-ID: CVE-2026-34600)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote user to disclose sensitive information.

The vulnerability exists due to improper access control in the delta API and ChangeModel.delta when synchronizing shared items. A remote user can trigger synchronization after access to a shared note has been removed to disclose sensitive information.

Only instances with DELTA_INCLUDES_ITEMS enabled are vulnerable. User interaction is required to perform synchronization.

Remediation

Install update from vendor's website.

References

• https://github.com/laurent22/joplin/security/advisories/GHSA-88x4-77rc-jw94
• https://github.com/laurent22/joplin/issues/14110