How severe is CVE-2021-3331?

CVE-2021-3331 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-3331 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3331?

CVE-2021-3331 affects Winscp. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3331?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-3331 published?

CVE-2021-3331 was published on 2021-01-27 and last updated on 2026-06-17.

CVE-2021-3331

CVE-2021-3331 is a critical-severity vulnerability in Winscp with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 7% (94th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Winscp
Published: 2021-01-27
Last modified: 2026-06-17

Description

WinSCP before 5.17.10 allows remote attackers to execute arbitrary programs when the URL handler encounters a crafted URL that loads session settings. (For example, this is exploitable in a default installation in which WinSCP is the handler for sftp:// URLs.)

Frequently asked questions

What is CVE-2021-3331?: WinSCP before 5.17.10 allows remote attackers to execute arbitrary programs when the URL handler encounters a crafted URL that loads session settings. (For example, this is exploitable in a default installation in which WinSCP is the handler for sftp:// URLs.)
How severe is CVE-2021-3331?: CVE-2021-3331 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-3331 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3331?: CVE-2021-3331 affects Winscp. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3331?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-3331 published?: CVE-2021-3331 was published on 2021-01-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:winscp:winscp:*:*:*:*:*:*:*:*

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