CVE-2021-27646

Name: CVE-2021-27646
Creator: NVD / NIST
Published: 2021-03-12T07:15:13.717+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.79%

Last modified Jun 17, 2026

CVE-2021-27646 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Use After Free 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.. EPSS estimates a 3.79% chance of exploitation in the next 30 days.

Description

Use After Free 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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.79%

88.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Synology	Diskstation Manager	< 6.2.3-25426-3

References

https://www.synology.com/security/advisory/Synology_SA_20_26Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-339/Not Applicable
https://www.zerodayinitiative.com/advisories/ZDI-21-340/Third Party Advisory, VDB Entry
https://www.synology.com/security/advisory/Synology_SA_20_26Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-339/Not Applicable
https://www.zerodayinitiative.com/advisories/ZDI-21-340/Third Party Advisory, VDB Entry

Timeline

Published: Mar 12, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-27646?

Use After Free 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.

How severe is CVE-2021-27646?

CVE-2021-27646 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.79% probability of exploitation in the next 30 days.

How do I fix CVE-2021-27646?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27646?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST