What’s Vulnerable › Vulnerabilities

CVE-2021-27649

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-23 · updated 2026-06-17
• Weakness: CWE-416

Description

Use after free vulnerability in file transfer protocol component in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows remote attackers to execute arbitrary code via unspecified vectors.

Affected products

• Synology DiskStation Manager: from 6.2 before 6.2.3-25426-3 — fixed in 6.2.3-25426-3
• Synology Diskstation Manager Unified Controller: before 3.1-23033 — fixed in 3.1-23033

How to fix

Upgrade to a fixed version: Synology DiskStation Manager 6.2.3-25426-3; Synology Diskstation Manager Unified Controller 3.1-23033. Check the vendor advisory for mitigations.

References

• https://www.synology.com/security/advisory/Synology_SA_20_26
• https://www.synology.com/security/advisory/Synology_SA_20_26

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