What is CVE-2025-66593?

CVE-2025-66593 is a medium-severity vulnerability in Synology Assistant, classified under Origin Validation Error. CVSS score: 6.1/10. Published 2026-05-27.

How severe is CVE-2025-66593?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Vulnerability in Synology Assistant

CVE-2025-66593

An origin validation error vulnerability in Synology Assistant before 7.0.6-50085 allows local users to write arbitrary files with restricted content and conduct denial-of-service during installation.

Published 2026-05-27 · last modified 2026-10-07.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H.

EPSS exploit prediction

EPSS: 0.001 (0.3th percentile), scored 2026-11-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 0th percentile — 0.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

www.synology.com/en-global/security/advisory/Synology_SA_25_17 (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2025-66593?: CVE-2025-66593 is a medium-severity vulnerability in Synology Assistant, classified under Origin Validation Error. CVSS score: 6.1/10. Published 2026-05-27.
How severe is CVE-2025-66593?: Medium severity. CVSS v3 base score is 6.1 out of 10.