CVE-2026-86174 in Plane
Summary
by MITRE • 09/05/2026
Plane through 1.4.2 fails to validate that issues belong to the deploy board's project in the public comment endpoint. Authenticated attackers can post comments to arbitrary issues across workspaces by supplying an issue_id parameter to the public deploy-board comment endpoint.
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Analysis
by VulDB Data Team • 09/05/2026
The vulnerability identified involves a critical authorization failure within the Plane application, specifically affecting versions up through 1.4.2. The core technical flaw resides in the public comment endpoint associated with the deploy board functionality. This endpoint is designed to allow users or systems to post comments on issues related to deployment activities. However, the implementation fails to perform adequate server-side validation to ensure that the issue identified by the provided issue_id parameter actually belongs to the project context of the authenticated user's current deploy board workspace. In a properly secured system, any request targeting an issue should verify that the requesting entity has explicit permission to interact with that specific resource within its authorized scope. The absence of this check creates a direct path for unauthorized access and manipulation of data across organizational boundaries.
From a technical perspective, this is a classic example of Broken Access Control, where the application relies on client-side assumptions or lacks sufficient server-side enforcement of object-level permissions. An attacker who possesses valid authentication credentials can exploit this weakness by crafting HTTP requests that include an issue_id belonging to a different project within the same organization or workspace. Because the endpoint does not cross-reference the target issue's ownership against the authenticated user's permitted projects, the system accepts and processes these maliciously crafted inputs. This allows for the injection of comments into issues that the attacker should not have access to view or modify, effectively bypassing logical security controls intended to isolate project data.
The operational impact of this vulnerability is significant in terms of confidentiality and integrity. Confidentiality is compromised because authenticated users can potentially infer information about other projects by observing error messages or successful comment submissions on issues they are not supposed to see. Integrity is directly impacted as attackers can post misleading, malicious, or spammy comments on critical deployment-related issues across various workspaces. This could disrupt development workflows, confuse team members regarding the status of specific features or bugs, and potentially be used for social engineering attacks if the comments contain deceptive information. In a collaborative software development environment, such unauthorized interference undermines trust in the issue tracking system's reliability.
This vulnerability aligns with CWE-284 Improper Access Control, specifically reflecting scenarios where access control decisions are not enforced properly on sensitive objects. It also maps to MITRE ATT&CK technique T1078 Valid Accounts, as it requires valid authentication but exploits misconfigured permissions rather than stolen credentials. Furthermore, the ability to interact with resources outside of one's authorized scope relates to CWE-639 Authorization Bypass Through User-Controlled Key. The exploitation does not require complex binary manipulation or memory corruption; instead, it leverages simple HTTP parameter tampering, making it easily exploitable by automated tools and posing a low barrier to entry for attackers who have obtained valid user credentials through phishing or other means.
Mitigation strategies must focus on implementing robust server-side authorization checks at the API level. Developers should ensure that every request to modify or access an issue verifies that the authenticated user has explicit read or write permissions for the specific project associated with that issue. This involves querying the database to confirm the relationship between the user, their workspace memberships, and the target issue's project ID before processing any comment submission. Additionally, implementing principle of least privilege ensures that users only have access to resources necessary for their role. Regular security audits and static code analysis focused on authorization logic can help identify similar flaws in other endpoints. For organizations using Plane versions prior to 1.4.3, upgrading to the patched version is the primary remediation step, as this issue has been addressed by enforcing stricter validation rules on public-facing endpoints within the deploy board module.