makeplane Plane up to 1.3.x Signup Flow improper authentication

Summaryinfo

A vulnerability, which was classified as critical, has been found in makeplane Plane up to 1.3.x. This affects an unknown part of the component Signup Flow. This manipulation causes improper authentication. This vulnerability is handled as CVE-2026-105639. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in makeplane Plane up to 1.3.x. It has been declared as critical. Affected by this vulnerability is an unknown functionality of the component Signup Flow. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Plane is an open-source project management tool. Prior to 1.4.0, Plane's signup flow creates a logged-in User row for any submitted email without an out-of-band ownership check, while User.email is unique=True. The authenticated user can call GET /api/users/me/workspaces/invitations/, which returns each WorkspaceMemberInvite whose email matches request.user.email. WorkSpaceMemberInviteSerializer uses fields = "all", exposing the token that protects the invitation join endpoint. An unauthenticated attacker who knows a target's email can register an account using that address, enumerate pending invitations, and accept an invitation as the target, joining a workspace at the invited role. The term pre-auth describes the attacker's initial state: the attacker has no credential before signup, while the enumeration and join requests use the session created by that signup. This issue is fixed in 1.4.0.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-105639 since 10/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available.

Upgrading to version 1.4.0 eliminates this vulnerability.

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Productinfo

Vendor

• makeplane

Name

• Plane

Version

• 1.0
• 1.1
• 1.2
• 1.3

Website

• Product: https://github.com/makeplane/plane/

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