What is CVE-2018-3780?

CVE-2018-3780 is a medium-severity vulnerability in Nextcloud Nextcloud/server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2018-08-13.

How severe is CVE-2018-3780?

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

XSS in Nextcloud Nextcloud/server

CVE-2018-3780

A missing sanitization of search results for an autocomplete field in NextCloud Server <13.0.5 could lead to a stored XSS requiring user-interaction. The missing sanitization only affected user names, hence malicious search results could only be crafted by authenticated users.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2018-08-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.6% 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 Nextcloud/server — versions >13.0.5
Nextcloud Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

nextcloud.com/security/advisory/ (Vendor Advisory)
hackerone.com/reports/383117 (Third Party Advisory)

Frequently asked questions

What is CVE-2018-3780?: CVE-2018-3780 is a medium-severity vulnerability in Nextcloud Nextcloud/server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2018-08-13.
How severe is CVE-2018-3780?: Medium severity. CVSS v3 base score is 5.4 out of 10.