# CVE-2026-55561: InvoicePlane: Guest user IDOR in quote approval and rejection


- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-6xj3-274m-4mvg

## What is CVE-2026-55561?

CVE-2026-55561 is a medium-severity vulnerability in InvoicePlane, published on 28 Oct 2026. 

### Official description

InvoicePlane is a self-hosted open source application for managing invoices, clients, and payments. Prior to 1.7.2-beta-1, guest users can approve or reject quotes belonging to any client, not just their assigned clients. The `approve()` and `reject()` methods in the Guest Quotes controller, `application/modules/guest/controllers/Quotes.php`, call `approve_quote_by_id($quote_id)` and `reject_quote_by_id($quote_id)` directly without the `where_in('ip_quotes.client_id', $this->user_clients)` scoping that sibling methods use. A guest user assigned to one client can change another client's quote status by supplying sequential integer `quote_id` values, and `email_quote_status()` also sends notification emails. Additionally, `generate_pdf()` calls `mark_viewed($quote_id)` before checking the client scope, allowing a guest user to mark another client's quote as viewed. These issues are fixed in version 1.7.2-beta-1 and the subsequent stable version 1.7.2.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-55561?


## How do I fix CVE-2026-55561?

No fix has been published for CVE-2026-55561 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55561 being exploited?

There is no known exploitation of CVE-2026-55561 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55561 and fix it if it is affected.

What it is: CVE-2026-55561 is a medium-severity vulnerability in InvoicePlane, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-55561 in the wild and no public exploit code.

Affected product: InvoicePlane. 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-2026-55561/ (Markdown: https://insights.sbomify.com/CVE-2026-55561/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55561
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55561
- OSV: https://osv.dev/vulnerability/CVE-2026-55561

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55561/
Summaries are generated and may contain mistakes; the official description above is the record.