PatchTheCVECVE-2021-3331: WinSCP before 5.17.10 allows remote attackers to execute arbitrary programs when the URL handler encounters a
CVE-2021-3331 is a critical-severity flaw (CVSS 9.8) affecting winscp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.)
Why this priority
- Critical severity
- EPSS top 5%: very likely to be exploited
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 7.7% (top 5%) |
| CISA exploited list | No |
| Published | 2021-01-27 |
| Last modified | 2026-10-08 |
Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-3331?
winscp: upgrade to 5.17.10. Exact commands for each OS are on this page.
Is CVE-2021-3331 being exploited?
CVE-2021-3331 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-3331 affect?
CVE-2021-3331 affects winscp. Severity is critical (CVSS 9.8). 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 handle
How urgent is CVE-2021-3331?
Priority 63/100. Critical severity; EPSS top 5%: very likely to be exploited; Remotely exploitable, no login, no user action
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