What is CVE-2019-15618?

CVE-2019-15618 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2020-02-04.

How severe is CVE-2019-15618?

Medium severity. CVSS v3 base score is 4.8 out of 10.

XSS in Nextcloud Server

CVE-2019-15618

Missing escaping of HTML in the Updater of Nextcloud 15.0.5 allowed a reflected XSS when starting the updater from a malicious location.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2020-02-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (52.4th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Nextcloud Server
Nextcloud Server — versions 15.0.6

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

hackerone.com/reports/515484 (Permissions Required)
nextcloud.com/security/advisory/ (Vendor Advisory)

Frequently asked questions

What is CVE-2019-15618?: CVE-2019-15618 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2020-02-04.
How severe is CVE-2019-15618?: Medium severity. CVSS v3 base score is 4.8 out of 10.