CVE-2021-26561
Synology
- Published
- 26 February 2021
- Last modified
- 17 June 2026
- CVSS
- 8.1 v3.1
- Severity
- high
- EPSS
- 2.0% (80th pct)
- CISA KEV
- Not listed
- NVD status
- Modified
- Weaknesses
- CWE-121, CWE-119
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Description
Stack-based buffer overflow vulnerability in synoagentregisterd in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows man-in-the-middle attackers to execute arbitrary code via syno_finder_site HTTP header.
Exploitation
Not listed in the CISA Known Exploited Vulnerabilities catalogue as of 2026.09.04. That is an absence of confirmed public exploitation, not evidence that exploitation has not occurred. EPSS models a 2.0% probability of exploitation activity in the next 30 days.
Affected products
| Product | Vendor | Type | Versions named |
|---|---|---|---|
| VS960HD | Synology | unknown | < 2.2.3-1505, < 2.3.6-1720 |
References
Vendor advisory and patch
- https://www.synology.com/security/advisory/Synology_SA_20_26
- https://www.synology.com/security/advisory/Synology_SA_20_26
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1159 exploit
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1159 exploit
Record assembled from NVD, CISA KEV 2026.09.04 and FIRST EPSS 2026-09-04. Affected products are those NVD's CPE configuration names that fall inside this site's scope; a CVE may affect products outside it.