What is CVE-2017-0891?

CVE-2017-0891 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2017-05-08.

How severe is CVE-2017-0891?

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

XSS in Nextcloud Server

CVE-2017-0891

Nextcloud Server before 9.0.58 and 10.0.5 and 11.0.3 are vulnerable to an inadequate escaping of error messages leading to XSS vulnerabilities in multiple components.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2017-05-08 · 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: 0.006 (48.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 48.7% 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 — versions before 9.0.58 and 10.0.5 and 11.0.3
Nextcloud Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

nextcloud.com/security/advisory/ (Vendor Advisory)
hackerone.com/reports/216812 (VDB Entry, Third Party Advisory)

Frequently asked questions

What is CVE-2017-0891?: CVE-2017-0891 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2017-05-08.
How severe is CVE-2017-0891?: Medium severity. CVSS v3 base score is 5.4 out of 10.