CVE-2021-43817

8.2 HIGH 0.7% exploit odds Fix listed

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. High risk of data tampering.
Exploit odds: 0.7% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2021-12-13 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 04:11 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.7% in the next 30 days (EPSS).
Severity: 8.2 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2021-12-13 20:15 UTC
Last modified: 2026-06-17 04:11 UTC
Exploit probability: 0.7% · EPSS, next 30 days
Weakness: CWE-79 · Cross-site scripting
Record status: Modified

Affected

Collabora Online < 4.2.20
Collabora Online < 6.4.16

Attack profile CVSS 3.1 · 8.2

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: High
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2021-43817.md and follow it. Check whether this project is affected by CVE-2021-43817. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record