What is CVE-2020-8294?

CVE-2020-8294 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-02-03.

How severe is CVE-2020-8294?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Nextcloud Server

CVE-2020-8294

A missing link validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows execution of a stored XSS attack using Internet Explorer when saving a 'javascript:' URL in markdown format.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-02-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.009 (58.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 58.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Nextcloud Server
Nextcloud Server — versions Fixed in 20.0.2, 19.0.5, 18.0.11

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

hackerone.com/reports/1023787 (Permissions Required, Third Party Advisory)
nextcloud.com/security/advisory/ (Vendor Advisory)

Frequently asked questions

What is CVE-2020-8294?: CVE-2020-8294 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-02-03.
How severe is CVE-2020-8294?: Medium severity. CVSS v3 base score is 5.4 out of 10.