What is CVE-2021-26563?

CVE-2021-26563 is a high-severity vulnerability in Synology Diskstation Manager, classified under Incorrect Authorization. CVSS score: 8.2/10. Published 2021-02-26.

How severe is CVE-2021-26563?

High severity. CVSS v3 base score is 8.2 out of 10.

Auth bypass in Synology Diskstation Manager

CVE-2021-26563

Incorrect authorization vulnerability in synoagentregisterd in Synology DiskStation Manager (DSM) before 6.2.4-25553 allows local users to execute arbitrary code via unspecified vectors.

Vulnerability class: Broken Access Control

Published 2021-02-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (42.5th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 42.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Synology Diskstation Manager
Synology Diskstation Manager (Dsm) — versions unspecified
Synology Diskstation Manager Unified Controller — versions 3.0
Synology Skynas
Synology Skynas Firmware
Synology Uc3200
Synology Vs960hd
Synology Vs960hd Firmware

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

www.talosintelligence.com/vulnerability_reports/TALOS-2020-1158 (Exploit, Third Party Advisory)
www.synology.com/security/advisory/Synology_SA_21_03 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-26563?: CVE-2021-26563 is a high-severity vulnerability in Synology Diskstation Manager, classified under Incorrect Authorization. CVSS score: 8.2/10. Published 2021-02-26.
How severe is CVE-2021-26563?: High severity. CVSS v3 base score is 8.2 out of 10.