High-severity VPN client PIN exposure could disrupt remote access; affects widely used Synology SSL VPN Client.
CVE-2021-47961
Plaintext PIN storage in Synology SSL VPN Client before 1.4.5-0684.
Is CVE-2021-47961 being exploited?
Not confirmed. CVE-2021-47961 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.32% probability of exploitation in the next 30 days.
How severe is CVE-2021-47961?
CVE-2021-47961 is rated High with a CVSS score of 8.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-47961?
Yes. A fix has been recorded for CVE-2021-47961. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-47961 affect?
CVE-2021-47961 affects Synology SSL VPN Client (pre-1.4.5-0684). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2021-47961?
Update to 1.4.5-0684 or newer; review PIN handling and VPN configs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can read/modify user PIN, enabling unauthorized VPN config and potential traffic interception.
Patch when possible
- affected< 1.4.5-0684
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.