What is CVE-2019-15617?

CVE-2019-15617 is a medium-severity vulnerability in Nextcloud Server, classified under Improper Authentication. CVSS score: 5.4/10. Published 2020-02-04.

How severe is CVE-2019-15617?

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

Auth bypass in Nextcloud Server

CVE-2019-15617

A missing check in Nextcloud Server 17.0.0 allowed an attacker to set up a new second factor when trying to login.

Vulnerability class: Broken Authentication

Published 2020-02-04 · 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:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (46.9th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Nextcloud Server
Nextcloud Server — versions 17.0.1

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

hackerone.com/reports/722748 (Permissions Required)
nextcloud.com/security/advisory/ (Vendor Advisory)

Frequently asked questions

What is CVE-2019-15617?: CVE-2019-15617 is a medium-severity vulnerability in Nextcloud Server, classified under Improper Authentication. CVSS score: 5.4/10. Published 2020-02-04.
How severe is CVE-2019-15617?: Medium severity. CVSS v3 base score is 5.4 out of 10.