What is CVE-2018-8921?

CVE-2018-8921 is a medium-severity vulnerability in Synology Drive, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2018-06-01.

How severe is CVE-2018-8921?

Medium severity. CVSS v3 base score is 6.5 out of 10.

XSS in Synology Drive

CVE-2018-8921

Cross-site scripting (XSS) vulnerability in File Sharing Notify Toast in Synology Drive before 1.0.2-10275 allows remote authenticated users to inject arbitrary web script or HTML via the malicious file name.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2018-06-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.006 (47.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.7% 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

Synology Drive — versions unspecified
Synology Drive Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.synology.com/en-global/support/security/Synology_SA_18_11 (Vendor Advisory)

Frequently asked questions

What is CVE-2018-8921?: CVE-2018-8921 is a medium-severity vulnerability in Synology Drive, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2018-06-01.
How severe is CVE-2018-8921?: Medium severity. CVSS v3 base score is 6.5 out of 10.