What is CVE-2021-34812?

CVE-2021-34812 is a medium-severity vulnerability in Synology Calendar, classified under Use of Hard-coded Credentials. CVSS score: 5.8/10. Published 2021-06-18.

How severe is CVE-2021-34812?

Medium severity. CVSS v3 base score is 5.8 out of 10.

Vulnerability in Synology Calendar

CVE-2021-34812

Use of hard-coded credentials vulnerability in php component in Synology Calendar before 2.4.0-0761 allows remote attackers to obtain sensitive information via unspecified vectors.

Published 2021-06-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.011 (64.8th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 64.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Synology Calendar
Synology Calendar — versions unspecified

Weakness classification (CWE)

CWE-798 — Use of Hard-coded Credentials

References

www.synology.com/security/advisory/Synology_SA_21_12 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-34812?: CVE-2021-34812 is a medium-severity vulnerability in Synology Calendar, classified under Use of Hard-coded Credentials. CVSS score: 5.8/10. Published 2021-06-18.
How severe is CVE-2021-34812?: Medium severity. CVSS v3 base score is 5.8 out of 10.