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

Status: published. Published: 2026-10-28. Updated: 2026-11-03.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- InvoicePlane / InvoicePlane: < 1.7.2-beta-1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); 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; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.27% as of 2026-11-02; percentile 19.92%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-639

## Exploit evidence

- exploit: https://github.com/InvoicePlane/InvoicePlane/security/advisories/GHSA-6xj3-274m-4mvg (ADP: CISA-ADP)

## References

- https://github.com/InvoicePlane/InvoicePlane/security/advisories/GHSA-6xj3-274m-4mvg (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/InvoicePlane/InvoicePlane/pull/1413 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/pull/1471 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/commit/424dc44eb54030b93176bb08cba07ba12d7ae451 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/commit/fca7792a24de0a749d881cbbe4af6f58e9545d20 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/releases/tag/v1.7.2 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/releases/tag/v1.7.2-beta-1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/InvoicePlane/InvoicePlane/security/advisories/GHSA-6xj3-274m-4mvg (ADP: CISA-ADP; exploit)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-55561; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-55561; retrieved 2026-11-03; source updated Not reported

Revision: 897b5be57a74551f0202f1a916e7bb616b5867f916a5eea2c3df373031ef5b61

Canonical: https://y2.dev/cve/CVE-2026-55561

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