CVE-2021-27852

Name: CVE-2021-27852
Creator: NVD / NIST
Published: 2021-05-27T21:15:20.567+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 31.95%

Last modified Jun 17, 2026

CVE-2021-27852 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code. This issue affects: Checkbox Survey versions prior to 7.. CISA has confirmed active exploitation in the wild. EPSS estimates a 31.95% chance of exploitation in the next 30 days.

Description

Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code. This issue affects: Checkbox Survey versions prior to 7.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

31.95%

98.1th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by May 2, 2022.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Checkbox	Survey	< 7.0

References

https://www.kb.cert.org/vuls/id/706695Third Party Advisory, US Government Resource
https://www.kb.cert.org/vuls/id/706695Third Party Advisory, US Government Resource
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27852US Government Resource

Timeline

Published: May 27, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-27852?

How severe is CVE-2021-27852?

CVE-2021-27852 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 31.95% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-27852?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27852?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST