CVE-2026-104965 in Plane
Summary
by MITRE • 10/05/2026
Plane is an open-source project management tool. Prior to 1.4.0, the issue-relation endpoint accepts issue UUIDs in the request body without validating that they belong to the caller's workspace. An authenticated user can create relations linking their own issues to issues in any other workspace on the instance, leaking issue metadata through activity events. This issue is fixed in 1.4.0.
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Analysis
by VulDB Data Team • 10/05/2026
The vulnerability identified in Plane prior to version 1.4.0 represents a critical failure in server-side access control mechanisms within an open-source project management platform. The core technical flaw resides in the issue-relation endpoint, which processes requests containing Uniform Resource Identifiers (UUIDs) for issues that users wish to link together. In secure software architecture, when a user initiates an action involving multiple resources, the backend must verify not only that the initiating user has permission to perform the action but also that all referenced resources are within the authorized scope of that user's permissions or organizational boundaries. Plane failed to implement this validation step for workspace isolation checks during the creation of issue relations. Consequently, the application accepted UUIDs pointing to issues located in workspaces other than the one associated with the authenticated caller without performing any authorization check to confirm ownership or membership rights within those target workspaces.
This lack of proper object-level access control allows an authenticated attacker to exploit the functionality by crafting malicious requests that include identifiers for issues belonging to different, potentially sensitive, workspaces on the same instance. By successfully creating these cross-workspace relations, the attacker establishes a logical link between their own controlled issues and those in restricted areas. While this action itself might seem benign as it merely creates a hyperlink or reference, the operational impact is significant due to how Plane handles activity events. The system generates detailed activity logs whenever such relationships are formed. These activity events often expose metadata associated with the linked resources, including issue titles, descriptions, status indicators, and potentially other sensitive attributes depending on the specific configuration of the instance. This mechanism effectively serves as a data exfiltration channel, allowing an attacker to enumerate or gather information about issues in workspaces they do not have direct access to view through standard interfaces.
From a classification perspective, this vulnerability aligns with CWE-284 Improper Access Control and specifically falls under the category of Insecure Direct Object References (CWE-639) where the application uses user-supplied input directly as an index or key without sufficient validation against access control policies. Furthermore, in terms of tactical mapping within the MITRE ATT&CK framework, this behavior facilitates Discovery techniques such as Account Enumeration or Application Data Discovery. The attacker leverages a legitimate feature to gather intelligence about other parts of the system that should remain isolated, thereby expanding their understanding of the target environment's structure and content without triggering typical intrusion detection alerts associated with unauthorized data access attempts.
The resolution for this issue was implemented in version 1.4.0 by enforcing strict workspace boundary checks on the backend before processing any relation creation requests. Developers must ensure that every resource identifier included in a request is validated against the current user's authorized workspaces, rejecting any attempt to link resources outside these boundaries with an appropriate authorization error. For organizations still running versions prior to 1.4.0, immediate upgrading is strongly recommended to close this information leakage vector. Additionally, until the upgrade can be performed, administrators should consider implementing network-level controls or Web Application Firewall rules that restrict access to the affected endpoint based on IP reputation if possible, although application-layer patching remains the definitive mitigation strategy for such logic flaws.