What is CVE-2018-8927?

CVE-2018-8927 is a medium-severity vulnerability in Synology Calendar, classified under Incorrect Authorization. CVSS score: 5.4/10. Published 2018-06-14.

How severe is CVE-2018-8927?

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

Auth bypass in Synology Calendar

CVE-2018-8927

Improper authorization vulnerability in SYNO.Cal.Event in Calendar before 2.1.2-0511 allows remote authenticated users to create arbitrary events via the (1) cal_id or (2) original_cal_id parameter.

Vulnerability class: Broken Access Control

Published 2018-06-14 · 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:N/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.009 (58.4th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 58.4% 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

Synology Calendar — versions unspecified

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

www.synology.com/en-global/support/security/Synology_SA_18_16 (Vendor Advisory)

Frequently asked questions

What is CVE-2018-8927?: CVE-2018-8927 is a medium-severity vulnerability in Synology Calendar, classified under Incorrect Authorization. CVSS score: 5.4/10. Published 2018-06-14.
How severe is CVE-2018-8927?: Medium severity. CVSS v3 base score is 5.4 out of 10.