# CVE-2026-105639: Plane: Pre-auth workspace invitation hijack via email-squat and self-served invitation token leak in Plane


- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 5 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** GHSA-4vj8-p63v-8p24

## What is CVE-2026-105639?

CVE-2026-105639 is a critical vulnerability in makeplane plane, published on 5 Oct 2026. 

### Official description

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.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key), CWE-287 (Improper Authentication), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-105639?


## How do I fix CVE-2026-105639?

No fix has been published for CVE-2026-105639 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-105639 being exploited?

There is no known exploitation of CVE-2026-105639 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-105639 and fix it if it is affected.

What it is: CVE-2026-105639 is a critical vulnerability in makeplane plane, published on 5 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-105639 in the wild and no public exploit code.

Affected product: makeplane plane. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-105639/ (Markdown: https://insights.sbomify.com/CVE-2026-105639/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-105639
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-105639
- OSV: https://osv.dev/vulnerability/CVE-2026-105639

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-105639/
Summaries are generated and may contain mistakes; the official description above is the record.