CVE-2021-27852

What the flaw is

Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code.

Description as published by CISA. We have not independently reproduced it.

What CISA requires

Versions 6 and earlier for this product are end-of-life and must be removed from agency networks. Versions 7 and later are not considered vulnerable.

This deadline is binding on US federal civilian agencies under BOD 22-01. It is not a legal deadline for anyone else, but it is a useful urgency signal — CISA sets it by how actively the flaw is being used, not by CVSS.

Public exploit code

4 public repositories referencing this CVE have been catalogued on GitHub. Treat this as a strong signal to prioritise patching, not as a verified working exploit — many such repositories are scanners, write-ups or forks rather than functional code.

• ARPSyndicate/cve-scores
• Addy-shetty/Laazy_sqli-labs
• Ostorlab/KEV
• Ostorlab/known_exploited_vulnerbilities_detectors

Vendor advisories

• nvd.nist.gov/vuln/detail/CVE-2021-27852

Primary sources

• NVD entry — CVSS score, CPE list and references
• CISA KEV catalog — the source for this page
• CVE Record at cve.org