What’s Vulnerable › Vulnerabilities

CVE-2021-27647

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-12 · updated 2026-06-17
• Weakness: CWE-125

Description

Out-of-bounds Read vulnerability in iscsi_snapshot_comm_core in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows remote attackers to execute arbitrary code via crafted web requests.

Affected products

• Synology DiskStation Manager: before 6.2.3-25426-3 — fixed in 6.2.3-25426-3

How to fix

Upgrade to a fixed version: Synology DiskStation Manager 6.2.3-25426-3. Check the vendor advisory for mitigations.

References

• https://www.synology.com/security/advisory/Synology_SA_20_26
• https://www.zerodayinitiative.com/advisories/ZDI-21-339/
• https://www.synology.com/security/advisory/Synology_SA_20_26
• https://www.zerodayinitiative.com/advisories/ZDI-21-339/

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