Threat database

Collabora Online Built-in CODE Server before 26.4.303 (richdocumentscode), a Nextcloud app, allows remote code execution, as exploited in the wild in September and October 2026, a different vulnerability than CVE-2025-66208. This is an OS command injection in proxy.php when the CODE server isn't running (e.g., the product was recently restarted). The vulnerability is not present in standalone Collabora Online servers; only this deployment with CODE Server is affected.

A security vulnerability has been detected in Collabora KodExplorer up to 4.52. Affected by this issue is some unknown functionality of the file /app/controller/share.class.php of the component fileUpload Endpoint. The manipulation of the argument fileUpload leads to improper authorization. Remote exploitation of the attack is possible. The attack's complexity is rated as high. The exploitation is known to be difficult. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

CVE-2026-23623 is a medium severity vulnerability in Collabora Online that allows users with view-only permissions and no download rights to bypass access controls and download shared files by pressing Ctrl+Shift+S, despite the interface lacking download buttons. This improper authorization issue affects multiple versions prior to patched releases in 2026. The vulnerability impacts confidentiality by enabling unauthorized data retrieval without requiring authentication or user interaction beyond the keypress. It has a CVSS score of 5.3 and has not been observed exploited in the wild. European organizations using vulnerable versions of Collabora Online for document collaboration risk unauthorized data exposure. Mitigation requires updating to fixed versions 23.05.20.1, 24.

EPSS 0.2%VulnerabilityCollaboraOnline#cwe-285Germany+5

CVE-2025-66208 is a high-severity OS command injection vulnerability affecting Collabora Online's built-in CODE Server (richdocumentscode proxy) in versions prior to 25.04.702. This flaw allows unauthenticated remote attackers to execute arbitrary OS commands via the proxy.php interface, particularly when used with Nextcloud and an intermediate reverse proxy. The vulnerability arises from improper neutralization of special elements in OS commands (CWE-78). No user interaction or privileges are required, and the vulnerability has not yet been observed exploited in the wild. The issue is fixed in version 25.04.702.

EPSS 1.1%VulnerabilityCollaboraOnline#cwe-78Germany+7

Collabora Online is a collaborative online office suite based on LibreOffice technology. Users of Nextcloud with Collabora Online Built-in CODE Server app can be vulnerable to attack via proxy.php. This vulnerability has been fixed in Collabora Online - Built-in CODE Server (richdocumentscode) release 23.5.403. Users are advised to upgrade. There are no known workarounds for this vulnerability.

EPSS 0.4%VulnerabilityCollaboraOnline#cwe-79Germany+7