Is CVE-2021-43817 actively exploited?

No active exploitation of CVE-2021-43817 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-43817 be exploited remotely?

Yes. CVE-2021-43817 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-43817?

CVE-2021-43817 has a CVSS score of 6.1 (MEDIUM).

HOME VULNERABILITIESCVE-2021-43817

MEDIUM

CVE-2021-43817

CWE-79Published: December 13, 2021· Updated: Jun 17, 2026

6.1

CVSS v3.1

Official Description

Collabora Online is a collaborative online office suite based on LibreOffice technology. In affected versions a reflected XSS vulnerability was found in Collabora Online. An attacker could inject unescaped HTML into a variable as they created the Collabora Online iframe, and execute scripts inside the context of the Collabora Online iframe. This would give access to a small set of user settings stored in the browser, as well as the session's authentication token which was also passed in at iframe creation time. Users should upgrade to Collabora Online 6.4.16 or higher or Collabora Online 4.2.20 or higher. Collabora Online Development Edition 21.11 is not affected.

NVD Source

Technical Analysis

CVE-2021-43817 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.