CVE-2021-26569Known exploitationNetwork attack vector

Remote code execution via iscsi race

Published Mar 12, 2021 · Updated Sep 17, 2024

Race condition in Synology DiskStation Manager before 6.2.3-25426-3 allows remote attackers to execute code via crafted web requests. The iscsi_snapshot_comm_core component can use freed state when concurrent web-request handling races, enabling arbitrary code execution. No authentication or user interaction is required, so an attacker able to reach the web interface can compromise confidentiality, integrity, and availability.

CVSS severity9.8
Critical
EPSS probability2.18%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Race condition in Synology DiskStation Manager before 6.2.3-25426-3 allows remote attackers to execute code via crafted web requests. The iscsi_snapshot_comm_core component can use freed state when concurrent web-request handling races, enabling arbitrary code execution. No authentication or user interaction is required, so an attacker able to reach the web interface can compromise confidentiality, integrity, and availability.

The record

CVE
CVE-2021-26569
Published
Mar 12, 2021
Updated
Sep 17, 2024
Vendor
Synology
Product
Synology DiskStation Manager
Classifications
CWE-366, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <6.2.3-25426-3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Synology · Synology DiskStation Managerversion=unspecified <6.2.3-25426-3

Published CVSS scores

9.8SynologyCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-366Race Condition within a Thread
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo