# CVE-2021-26569

## Summary

- **CVE ID:** CVE-2021-26569
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-366
- **Published:** Mar 12, 2021
- **Last Modified:** Mar 13, 2026

## Description

Race Condition within a Thread 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 — Synology DiskStation Manager (DSM) (unspecified)

## References

- [CNA](https://www.synology.com/security/advisory/Synology_SA_20_26)
- [CNA](https://www.zerodayinitiative.com/advisories/ZDI-21-338/)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 1.75%
- **EPSS Percentile:** 82.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._