CVE-2021-47961

Q: How do I fix CVE-2021-47961?

Upgrade ssl vpn client to 1.4.5-0684 or later.

Q: Is CVE-2021-47961 being actively exploited?

Not that we know of. CVE-2021-47961 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.32% is the estimated probability that it will be exploited in the next 30 days. That is higher than 25% of all scored CVEs.

Q: How severe is CVE-2021-47961?

CVE-2021-47961 has a CVSS v3 base score of 8.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2021-47961 affect?

Published advisories record a fix for ssl vpn client (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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

25thpercentile

Low risk: more likely to be exploited than 25% 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%	-	-

Common questions

How do I fix CVE-2021-47961?

Upgrade ssl vpn client to 1.4.5-0684 or later.

Is CVE-2021-47961 being actively exploited?

Not that we know of. CVE-2021-47961 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.32% is the estimated probability that it will be exploited in the next 30 days. That is higher than 25% of all scored CVEs.

How severe is CVE-2021-47961?

CVE-2021-47961 has a CVSS v3 base score of 8.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2021-47961 affect?

Published advisories record a fix for ssl vpn client (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2021-47961

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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.