How severe is CVE-2021-47667?

CVE-2021-47667 has a CVSS 3.x base score of 10.0, 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-2021-47667 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 33% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2021-47667?

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.

Does CVE-2021-47667 have an EU (EUVD) identifier?

Yes. CVE-2021-47667 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34675.

When was CVE-2021-47667 published?

CVE-2021-47667 was published on 2025-04-05 and last updated on 2026-06-17.

CVE-2021-47667

CVE-2021-47667 is a critical-severity vulnerability with a CVSS 3.x base score of 10.0. Its EPSS exploit-prediction score of 33% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 33% (98th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-34675
Weakness: CWE-78
Published: 2025-04-05
Last modified: 2026-06-17

Description

An OS command injection vulnerability in lib/NSSDropoff.php in ZendTo 5.24-3 through 6.x before 6.10-7 allows unauthenticated remote attackers to execute arbitrary commands via shell metacharacters in the tmp_name parameter when dropping off a file via a POST /dropoff request.

Frequently asked questions

What is CVE-2021-47667?: An OS command injection vulnerability in lib/NSSDropoff.php in ZendTo 5.24-3 through 6.x before 6.10-7 allows unauthenticated remote attackers to execute arbitrary commands via shell metacharacters in the tmp_name parameter when dropping off a file via a POST /dropoff request.
How severe is CVE-2021-47667?: CVE-2021-47667 has a CVSS 3.x base score of 10.0, 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-2021-47667 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 33% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2021-47667?: 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.
Does CVE-2021-47667 have an EU (EUVD) identifier?: Yes. CVE-2021-47667 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34675.
When was CVE-2021-47667 published?: CVE-2021-47667 was published on 2025-04-05 and last updated on 2026-06-17.

References

https://projectblack.io/blog/zendto-nday-vulnerabilities/

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