CVE intelligence and bounded remediation

CVE-2021-26569 — Synology Diskstation Manager security vulnerability

Critical CVSS 9.8

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.

Severity
Critical
CVSS
9.8 (3.1)
Published
2021-03-12
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-366, CWE-362

Affected products

  • synology / diskstation_manager

Matched remediation archetype

Race condition, TOCTOU, and lifecycle synchronization

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Check exposure

  • Map concurrent actors, shared state, lock boundaries, signals, callbacks, retries, and check-then-use sequences in the affected path.
  • Determine whether untrusted users can influence timing, object names, filesystem state, or repeated state transitions.
  • Identify clustered and multi-process behavior that repository-local tests may not represent.

Remediate safely

  • Make the sensitive state transition atomic or protect it with a consistently ordered synchronization primitive.
  • Perform authorization and invariant checks on the same authoritative object and transaction used for the operation.
  • Use unique private resources, safe ownership transfer, and idempotent operations; add deterministic concurrency regression tests.

Authoritative sources

Complete CVE record and remediation plan

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