Plane: Broken Access Control - joinProject GraphQL mutation allows self-join into private (secret) projects

Plane is an open-source project management tool. Prior to 1.4.0, the GraphQL joinProject mutation lets any workspace member add themselves to any project in that workspace including network=0 (secret/private) projects they were never invited to and grants them a full Member role (read + write). The resolver checks only workspace-level membership/role and never checks the target project's visibility (network). This collapses project-level tenant isolation within a workspace: a low-privilege member can read and modify confidential data in every private project. This issue is fixed in 1.4.0.

Source published

5 Oct 2026 17:57:22 UTC

Source modified

5 Oct 2026 19:13:21 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N