CVE-2026-105786 in Joplin
Summary
by MITRE • 10/06/2026
Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Prior to 3.7.13, packages/server/src/models/ApplicationModel.ts accepts a caller-chosen application authorization identifier, applications/:id/confirm binds that identifier to a logged-in user through a generic consent page, and the public packages/server/src/routes/api/application_auth.ts endpoint passes it to ApplicationModel.createAppPassword without authenticating or binding the redeemer. An attacker can cause a victim to approve the attacker's identifier, redeem a durable application ID and password, and exchange the credential for a victim session with full read and write access to synchronized data. This vulnerability is fixed in 3.7.13.
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Analysis
by VulDB Data Team • 10/06/2026
The security flaw identified in Joplin versions prior to 3.7.13 represents a critical authentication bypass rooted in improper validation of authorization identifiers during the application password creation process. The vulnerability exists within the server-side logic that handles the binding of an application identifier to a user account. Specifically, the endpoint located at packages/server/src/routes/api/application_auth.ts accepts an application authorization identifier provided by the client without performing sufficient verification against the authenticated session context. This design flaw allows an attacker to supply their own chosen identifier rather than relying on server-generated or strictly bound tokens that would ensure integrity between the requestor and the intended recipient of the credentials.
The exploitation mechanism relies on a social engineering component combined with this technical weakness. An attacker initiates the process by providing a specific application authorization identifier, which is then presented to the victim through a generic consent page at applications/:id/confirm. Because the system fails to cryptographically bind or verify that the redeemer of this identifier matches the entity initiating the request, a victim who approves the prompt inadvertently authorizes the attacker's chosen identifier. This step effectively decouples the authorization grant from the actual user session making the request, creating a situation where consent is granted for an action not intended by the consenting party in terms of credential ownership.
Once the victim approves the request, the ApplicationModel.createAppPassword function generates durable application credentials associated with that attacker-controlled identifier and binds them to the victim's account. These credentials are persistent and do not expire automatically like standard session tokens. The attacker can then use these generated application ID and password pairs to authenticate against the Joplin server. Upon successful authentication, the system grants full read and write access to all synchronized data associated with the victim's account. This results in a complete compromise of confidentiality and integrity for the user's notes, lists, and other stored information, as there is no additional multi-factor verification or session validation step at this specific endpoint to prevent unauthorized redemption.
From an industry standard perspective, this vulnerability aligns closely with CWE-287, which describes Improper Authentication, specifically involving insufficiently verified credentials for application access. It also relates to CWE-345, Insufficient Verification of Data Authenticity, as the system fails to verify that the authorization identifier being redeemed is legitimately associated with the current user session context rather than an arbitrary value supplied by a third party. In terms of MITRE ATT&CK mapping, this behavior corresponds to T1078, Valid Accounts, where attackers leverage legitimate credentials obtained through deception or bypass techniques to maintain persistent access and exfiltrate data without triggering typical intrusion detection alerts associated with brute force or credential stuffing attacks.
Mitigation for this vulnerability requires immediate upgrading of the Joplin server components to version 3.7.13 or later, as these updates include fixes that enforce proper binding between the authorization identifier and the authenticated user session. For environments where an upgrade is not immediately feasible, administrators should implement strict input validation on the application_auth endpoint to ensure that identifiers are generated server-side rather than accepted from client inputs. Additionally, enforcing multi-factor authentication for account access can provide a secondary layer of defense, ensuring that even if credentials are compromised through this flow, unauthorized access remains blocked without the second factor. Regular auditing of API endpoints for similar patterns where consent flows lack strict origin and identity verification is recommended to prevent analogous issues in other services.