Secuno
ENNL
Book demo

CVE-2021-47961

Synology SSL VPN Client vulnerability

8.1 HIGHEPSS 0.32%
  1. Published10 Apr 2026

Description

A plaintext storage of a password vulnerability in Synology SSL VPN Client before 1.4.5-0684 allows remote attackers to access or influence the user's PIN code due to insecure storage. This may lead to unauthorized VPN configuration and potential interception of subsequent VPN traffic when combined with user interaction.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Affected products

Synology SSL VPN Client< 1.4.5-0684

Remediation

Fixed in
Synology SSL VPN Client≥ 1.4.5-0684

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2021-384898.2
HDD password plaintext is stored in a UEFI…
CVE-2026-557658.5
CloudNativePG is a platform designed to manage PostgreSQL databases within Kubernetes…
CVE-2026-332168.6
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging…
CVE-2024-550269.8
An issue in the reset_pj.cgi endpoint of Weintek cMT-3072XH2 easyweb v2.1.53, OS…
CVE-2026-216609.8
A Hardcoded Email Credentials Saved as Plaintext in Firmware (CWE-256: Plaintext…
CVE-2025-151139.3
Ksenia Security lares (legacy model) Home Automation version 1.6 contains an…

Frequently asked

Is CVE-2021-47961 being actively exploited?

CVE-2021-47961 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.32%.

How severe is CVE-2021-47961?

CVE-2021-47961 has a CVSS 3.1 base score of 8.1, rated high. EPSS estimates a 0.32% probability of exploitation.

Which products are affected by CVE-2021-47961?

Affected products include Synology SSL VPN Client.

How do I fix CVE-2021-47961?

Upgrade affected software to a fixed version, for example Synology SSL VPN Client 1.4.5-0684 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-47961 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.