Is CVE-2021-47961 in the CISA KEV catalog?

No. CVE-2021-47961 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-47961?

CVE-2021-47961 has a CVSS v3 base score of 8.1 (HIGH).

What is the EPSS score for CVE-2021-47961?

CVE-2021-47961 has an EPSS score of 0.32% (24th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-47961?

Upgrade ssl vpn client to 1.4.5-0684 or later.

CVE & CISA-KEV Catalog

CVE-2021-47961

HIGH

8.1

CVSS v3

NVD

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.

CWE-256

How to fix

Remediation Available

ssl vpn clientNVD

Affected:< 1.4.5-0684Fixed in:1.4.5-0684CVE-2021-47961derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.32%probability of exploitation in 30 days

24thpercentile

Low risk: more likely to be exploited than 24% of all known CVEs.

References

Vendor Advisory1

synology.com

Related Vulnerabilities

Other CWE-256 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-28736	High	7.1	2.5%	-	-
CVE-2019-10921	High	7.5	2.4%	-	Fix
CVE-2017-16714	Critical	9.8	2.4%	-	Fix
CVE-2024-26165	High	8.8	1.9%	-	Fix
CVE-2020-8183	High	7.5	1.9%	-	Fix
CVE-2020-6961	Critical	10.0	1.6%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-29.