CVE-2023-52951

Synology Note Station Client ≤ 2.2.4-703

Published

03 June 2026

Modified

22 July 2026

CVSS Score v3.1 5.9

Click a component to see what it means

Raw vector

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

EPSS Score 0.0013 2th percentile

Risk Priority 43 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-52951 is a medium-severity Cleartext Transmission of Sensitive Information (CWE-319) vulnerability in Synology Note Station Client. Its CVSS base score is 5.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Network Sniffing (T1040); ranked at the 2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-8 (Transmission Confidentiality and Integrity) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2023-60579

Vulnerability Data

A cleartext transmission of sensitive information vulnerability in Synology Note Station Client before 2.2.4-703 allows man-in-the-middle attackers to obtain user credential.

CWE(s): CWE-319

Related Threats

MITRE ATT&CK Enterprise Techniques

T1040 Network Sniffing Credential Access

Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network.

attack.mitre.org →

T1003.004 LSA Secrets Credential Access

Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.

attack.mitre.org →

T1003.008 /etc/passwd and /etc/shadow Credential Access

Adversaries may attempt to dump the contents of <code>/etc/passwd</code> and <code>/etc/shadow</code> to enable offline password cracking.

attack.mitre.org →

T1006 Direct Volume Access Stealth

Adversaries may directly access a volume to bypass file access controls and file system monitoring.

attack.mitre.org →

T1007 System Service Discovery Discovery

Adversaries may try to gather information about registered local system services.

attack.mitre.org →

T1010 Application Window Discovery Discovery

Adversaries may attempt to get a listing of open application windows.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

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Affected Assets

synology

note station client

≤ 2.2.4-703

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SC-8 Transmission Confidentiality and Integrity good match

SC-8 directly requires protecting confidentiality of transmitted information, which structurally eliminates cleartext transmission of sensitive data.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.DS-02 partial match

blocks

Encryption of data-in-transit directly prevents cleartext transmission while the control also addresses integrity and availability.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match

blocks

Mandating cryptographic protection and stronger authentication on public networks stops the transmission of plaintext sensitive information.

A.5.15 Access control partial match

removes

A.5.16 Identity management partial match

removes

A.5.17 Authentication information partial match

removes

A.5.18 Access rights partial match

removes

A.8.10 Information deletion partial match